The 350 engine is great for swapping into that truck. The V-8 was an option in that model & all factory parts are available. Putting the auto trans in is another story. You have to remove the crossmember under the bell houseing & get crossmembers for the engine & trans. Leaving it with a manual trans is easier.
I am going to do my 56 this winter & use a Camero T-5.
