The rear axle from the '84 will be to wide. Look for a 4x4 S10 or Blazer, I believe they will have the correct width.
You will need a different bell housing for a V8 to early transmission. Someone will come along with the correct year of bell housing. You will also need different motor mounts when going to a V8.
It may not be the cheapest option, but rebuilding the OEM engine and replacing the rear ring & pinion would get you highway speeds without all the aftermarket parts or adapters.
