Dear Mr. Rees;
Ken is right on.
Also; The 'Cadilac 6' can be made to over 300cid & will bolt right in with few modifications. You and your friends could install in a weekend with hand tools.
Remember these trucks with 216" (85 hp) hauled cargo all over the USA from WWII on. The "Cadilac" will have close to 200hp.
Good luck, John M......