One ton would work but I would buy a two ton, you may need it for something heavier in the future.
The engine + trans weighs well below a ton. I would guess in the range of 1/4 ton.
A two ton hoist is going to be big and heavy. If you have unlimited storage space, I guess the big one could be OK. Maybe you will start restoring Mack trucks someday. Me, I'd go for the smallest, lightest hoist that will do the job safely.