once you open the bottom end, you got a coin toss engine, 50/50 is makes it past 200 miles, had one guy here a few years back, had a shop rebuild his engine, it was knocking before he got out the driveway. they rebuilt it again, and dont ya know, it was also sh it and started to knock before he could drive it. i think they even swapped out his block on the second rebuild.

on the rare flip side, people have done back yard rebuids and they worked out fine.