As long as they're both roller cam or non-roller cam then you're fine. But if, say, the '88 is non-roller and the '92 is roller, then you have to keep the correct gear for each engine with that engine.

I'll have to look into the different shaft diameter thing...

ON EDIT: Armed with my trusty digital calipers I just dug into my vast collection (or is that large pile...? Yes, I think the term "pile" would be more appropriate) of Ford parts and pulled out 2 distributors. 1 is a TFI unit from a recently acquired '93 T-bird 5.0 HO roller cam engine, the other is a Duraspark unit of indeterminate age but believed to be late-'70s vintage.

I took measurments of each of the shafts and discovered...that both measured .450". No difference in shaft diameter. There was a difference in shaft length however, the late-model unit being some 1/2" longer at the the tip. So I would say that they are indeed interchangeable. (Your results may vary.)