Or you could use a 235/261 or even a 270-302 GMC engine.These engines are more or less a bolt in.That way you need not change the steering or get into serious modifications .If you are not a street racer, an old inline 6 gives plenty of power for modern traffic, and retains the nostaligic look and sound.The best option is always the one that is inline with your skills, time and money.