86 up has the smaller crank flange for a one-piece seal. Also, center bolt valve covers became standard. Mounting points and bosses are the same from Generation 1 and 2 small blocks. LT1's (Gen 2) have reverse flow cooling.
I personally would look for a 94+ SBC in a truck and grab the Vortec heads and pick up a new intake.
Of if you are in a quick pinch, toss in the carb'd 350, pick up a holley fuel pressure regulator with return and plumb that to the carb. Then wire a relay to power the Distributor and to back-feed the TBI fuel pump through the priming lead as the computer will want to shut down the fuel pump without a valid tach signal. The TBI pump is a 1-bar (15psi) fuel pump.
