Hi BigMike-
Since CO has some similar engine swap laws for smog... I went through the same thing swapping an injected 350 into a friends 86 LC Wagon... For the Check-Engine Light I spliced into the choke light (not sure if the truck has a choke light or not) wiring, works like a charm and you keep the factory dash, etc... as for OBD II I believe that '96 was the first year all Auto Co's had to comply with the standard... (yeah was emissioned certified in CO a while back)... if the engine is out ot a 95.5 then it should still be Toy Diag... so they won't plug into it to pull codes like OBD II.
I missed the part about you swapping in some other dash/cluster? Whatcha putting in?
A