I have done research on this before and know it's not easy to find info. My latest search yielded the following link:
I don't think it's a good idea to build a hoist this way, especially not for v8 engines, but you might be interested.
The attached pic shows a hoist which is obviously made using a bottle jack, but unfortunately I have no more info on it. But I think this is the way to go to build a budget hoist.
Plans for building an engine stand which is suitable for v8s can be found on a German site:
The problem is if you don't understand German it could be difficult to follow.