In LTSpice i found the model attached, the schematic above shows what looks like one input & one output for each, the model attached has three pins, is this suitable for simulating this circuit?
The extra gates in parallel are just for extra drive current, they shouldn't effect much in the real world and they're just extra parts to slow down a simulation.
Any question, especially newby, you might ever ask about LTSpice has already been answered, probably several times, and can be keyword searched on the Yahoo LTSpice Forum. There are also a lot of spice models, symbols, examples in the FILES section on the Yahoo group.