All you need do is swap the computers. Wiring at the connector is the same. The only differences in programming and wiring would be a manual to automatic transmission.
You might need to take the V8 ignition switch as well so the ignition key matches what the computer security system is looking for. But these early security systems are a bit flakey in this regard some are sensitive, some are not to this.
The V6 uses the same fuel pump and fuel plumbing as the V8’s across the years you have. This is pretty standard from 87 through 92 the big difference is in the big block and the 4L80E transmission that came with those engines and in 1993 when the 4.3, 305, and 350 got the 4L60E; all of these changed the computer to include a transmission controller. However, the TBI part of these computers works just fine without a transmission to control. All of this changes for 1996 and up so stuff after 1995 is off the table. The 4.3 drifts into OBD 2 before the V8’s so getting into 94 and 95 you can find these 4.3’s and their vehicle systems do not interchange with the OBD 1, TBI versions.
Bogie