If you are already fuel injected (assuming you are TBI?) you CAN use your stock harness and add a few wires. That info is over at thirdgen.org.
It's a toss up with MAF, which is what the Corvette setup will be. MAF's are expensive when/if they fail, and the programming isn't as advanced that controls the system.
The Corvette setups use 58CC aluminum heads, the timing is likely going to be all wrong for an iron headed motor unless you use the heads too.
I had looked at the Corvette stuff myself, the fuel lines coming off the passenger rear of the engine looked like a REAL bear to deal with, the truck has VERY little room back there for extra parts.
Ryan can comment on this, but for emissions legality, if it's a concern, the Corvette intake should allow you to plumb EGR externally from the exhaust.
I believe '86 was the first year for VATS, which pretty much means you'll need another ECM or reprogramming.
Not trying to discourage, you'll just find lots of "little" things you hadn't considered before.