I would like to know if a 70's 351ci. Cleavland engine I have in my boat would bolt up to the transmission that is connected to a 4.9L straight six out of a 1996 f-150; and what systems would need modifacation.
Most marine engines run backward. To do that, they need different connecting rods and pistons, (or the assemblies are turned around), and a different cam shaft and distributor. As far as different engines bolting to different transmissions, your best bet is to find an older mechanic at a Ford dealership. There were a real lot of changes between the '70s and '90s, and Ford was never known to make a lot of stuff interchangeable like Chrysler did. Unless someone knows differently for certain, it's unlikely the two will bolt together.