Changing my 86 carb to 88 EFI, HELP!!!!!

[Russell]

You can physically bolt 305 heads onto a 350, but they have fairly small combustion chambers which puts your compression ratio through the roof, and usually have smaller valves too, which tends to choke the engine out.

I'd actually tend to suggest you just unbolt the engine from the 92 suburban, and bolt it straight into your 86. That way you don't have to worry about tuning anything but before you can drive the truck normally. Once you have it installed and running, then you'd probally just want to leave it just the way it is for now

If you are a big fan of the TBI, but want more oomph, take your 86's engine, and rebuild it from the ground up, with an EFI roller cam, set of good aftermarket heads etc. Something that'll make 300 horse under 4800 rpm, and swap that in, then take it somewhere to be dyno tuned.