I second Dave on the '50s & '60s frames the rivets are a pain to remove & weld, but welding is stronger. I do like the '69 & '70 chevy trucks. They look good and have trailing arms with coil springs on the rear....a good place to start, much better than leaf springs. Trucks are light in the rear and hard to get grip, weight transfer is the key.......

Just remember 600hp is useless if you can't get any grip......