318 timing chain.....and why the engine should come out.

Hard to tell how many miles you will get but, I can tell you that years ago before it was the norm to buy new crate engines or rotating assemblies, back when we didn't have so many options or parts or money available to us. We use to roll new rod and main bearings, maybe clean the pistons and reinstall with a new set of rings and oil pump. Maybe a valve job on the heads,timing chain/gears. They would run just fine for many miles.