Shosh,
I can't help as to a replacement for the 4583, I never seen one or used one, so I can't help with that I'm afraid.
However, I agree with alec_t, a system with seven segment displays is a good bet. Perhaps something that displays a time interval between two switches.
I did a project mainly using a PIC once based on this, but it is entirely possible to create the same overall effect with shift registers and a bit of Logic, that will easily fufill the specification.
You could of course create a complex logical function such as a multibit Multiplexer, a string of Full Adders with some form of display output,
Just chucking thoes ideas into the ether.
Sorry I'm not much use on the 4583 issue.
Fab Class sounds interesting, are you going to have to create and solder a PCB?
Owen.