Oh NO!! not another small block build

Back in the 80's, 90's mainly I built and restored a lot of Mopars. My engine guy was a country boy type, but a world class engine builder and sprint car driver. We never had to deal with rusty bores, just determine if too much out of round, if not, get rid of the ridge, hone,..... install new brings, rings, cam, many 383-440's were done. All ran well and lasted.
Funny part was as I got in to the late 90's and started using 400 and 440's from the late 70's instead of 60's blocks, seems like I kept finding engines with very little wear. I never did find out why. Was it better ring, better blocks ( dobt that), different gas, carburation??????
I have never had a magnum engine, but I keep reading about how little wear they have even with quite few miles. I have to assume it is due to FI ? Just a better air/fuel mixture.
RRR is right. Finding good rebuildable engine core gets harder all the time.