At least dead horses don't complain when you beat them, but that's a good point- - - - -if you've got a known good engine, swap it out and rebuild the original if you want to. I've got a Dodge V6 that fits two of my trucks, 10 years apart in age. The idea is to build up a spare, and swap it into whichever one needs an engine first, then play musical chairs with the take-out engine once it's rebuilt. I'll always have a spare built up and ready if things work out the way I plan.
Jerry