I have a 92 c1500 with a control brain, efi , v 6,gas tank fuel pump .i just bought a 355 to drop in it.no efi,and has manual fuel pump.no connection for control brain.is this going to be very complicated..if not can anyone assist on the process

Yes, this can and will get very complicated. You are attempting to go from a FI engine to a carb'd engine. The ECU won't know what the engine is doing and will not control the trans right. Keep everything the same. If you can, get the matching trans with the engine. Unless you are electronic 4wd, then you are going into unknown territory.