We built a pretty nice V8 Alpine some time back the cost of the drive train was 5K which included a 302,5 speed,8.8 rear axle and the drive shaft
being a fabricator machinest for years it was a fairly easy deal , we also fabricated a complete coil over front crosmember, this car was sold several months ago and shipped to Germany. I would not hesitate to do it again but maybe look at a modern 4 cylinder motor( plenty on todays market) there’s something to be said for going your own way,so to speak.