Your '76 engine is fine for turbocharging. Factory ZXT stuff will bolt on, and work fine, but I suspect the intake and exhaust ports will not match perfectly (doesn't the N42 have round exhaust ports, the turbo head has square ports...?). You will have to remove the pan to install the drain, so either swap it or modify your existing pan; equally easy. It is removable with the engine in, but you might have to lift the engine off the mounts a little bit.