Ha ha, i have been doing both lately because of this thing. I had to rebuild
an emissions valve with some plumbing supplies from Home Depot...not fun.
I just recently found out something in my state; you might try to see if it applies where you're at (maybe, maybe not - they only recently in 2007 changed the law here in AZ):
If you have a car that you can insure as a "collectible" vehicle (it is a special rider or something on the insurance that "tags" it as a "collectible"; from what I found, the vehicle has to be 30 years old, and there may be other restrictions on how much you can drive it, etc), then here in AZ, you can get an exemption on the emissions testing requirement.
I have an old 1979 full-size Bronco that has a 400M block V8; I bought it used off a guy in 2004, and spent a bunch of money replacing all the needed parts on it to make it pass emissions (the previous owner had removed them all, having had it tagged in Washington State, which didn't have emissions testing at that time). Well, every year I'd have to take my Bronco down to a shop to have it "quick tuned" just to get it to pass emissions, and I maybe only drove the thing 500 miles a year if that (I bought it originally for off-road use - the only time it has seen more miles was one trip in 2004 to Burning Man I took it on). Anyhow, I'm sick of doing that whole "quick tune" thing, so I did some research and found out about the new insurance law. It may end up costing me more on a yearly basis for the insurance if I can get it, but the benefit is that I can remove all of the power-robbing emission controls and do some interesting things with the truck (first thing, though, is to fix a backfire issue I'm having - but that very well may just be a tuning issue; one thing I want to do, which may ultimately cure that, is drop a 4bbl carb and hi-flow intake on it to replace the stock intake and 2bbl carb).
Dont let anyone tell you it's not a worthwhile car either.
Also, by registering a vehicle as Historic in this state it only requires
inspection every 3 years instead of every 2 years, and renewing the registration
is free. So you start to see the benefits right there.
We have something similar to that here as well, but it doesn't cover the emission requirement; if you car is registered historic, and is post-1976 (or is it 1966? I forget) model year, you still need to pass the emissions testing procedure - unless you have that new "collectible vehicle" insurance. Which they (MVD, state emissions testing place) never told me about (nor did my insurance company) the last time I had it done (in 2008); I even noted on the application for the de-insurance certificate that the reason it was being de-insured and un-registered was because it wouldn't pass emissions. One would think somebody could have told me about the new change (heck, even today, I only happened upon it accidentally - the thing is like buried, like they -don't- want you to know about it).
But, with this insurance rider (and you -don't- have to have it registered "historic" either, unless you want the special historic plates), you can bypass the emissions testing; it seems like the only requirements for a car being a "collectible" is that it is a) 30 years old or older, b) restored to original condition, c) or, alternatively, modified from its original stock condition. There also may be a minor requirement that it is something "shown" publicly (take the car once in a while to a car show, register and park it for people to look at). All items are basically determined by the insurance company; I have the intention of getting my engine work done, then once it is in good drivable condition, I've got some suspension work to have done on it, then some various trail modifications (custom front/rear bumpers, roof rack, fuel/water can carrier, slide/bump bars, skid plates, winch, etc); if I can swing it, I'm going to tell the guy I take it to for these kinds of mods to make the vehicle "functional Mad Max" (he shouldn't have to do much; it's already halfway there, the thing is so ugly). That should be enough mods to make it a public spectacle or something like that...
It's actually quite interesting to do this however. I had many much older cars
(pre 1960 or so) that were more worthy of restoration but made the mistake of getting
rid of them such as a 1961 Cadilac and a Dodge with push button transmission.
I imagine it would be even harder to get parts for them now though.
Well - that would depend on how much money, time and tenacity you have; for instance, you can still find people who make and sell through collector clubs wooden spoke wheels and such stuff; like really old, you-ain't-finding-it-no-place parts. Of course, this kind of restoration work, involving custom made from-the-ground-up parts (typically based on old plans, if available, or in the worst-case, measurements taken off of existing parts from another collector's vehicle, or perhaps even from a museum piece) - well, that takes more money than I'm willing to put into just about anything (the only thing I own that I plan to sink some money into getting restored back to "museum show quality", if I can do it, is my Altair 8800 - the biggest expense will likely involve a custom-made sheet-metal cover as the company that originally made the case, no longer does; I bought the machine from a local electronics junk yard about a year after they had stopped making the case, and got rid of the plans).