Why not repair the engine you already have?

A piston and injector refurb would get it going again.

A step further would be what I call a " junkyard rebuild". Fresh rod and main bearings, if the crank is slightly small that is OK. Resized connecting rods ( both ends ) used pistons, new rings, resurface the head , grind the valves and only replace guides that are excessively worn. Replace the timing chain. Resurface the oil pump cover , housing to get end clearance down. < this is where oil pumps lose volume / pressure when worn.

What you end up is that mythical " good used engine ". The above results in a crank bearings that will have reasonable life and not explode. Good ring seal however , due to worn pistons, the rings won't last 1 million miles. Valves with good sealing but , due to guide wobble , they won't last 1 million miles.

The risks are: A cracked piston due to metal fatigue, a body that won't outlast the engine. This last bit is why I do junk yard rebuilds for a car that isn't going to last forever.