James if I got sassy you would of know it.  Jenings stuff is great reading, a lot of of it is very outdated and extremely general.
 If you run a 250 and set squish at  much less that .030 you going to be replacing the head piston rod and probably crank.  Now as long as its a trailer queen and only ever idles it might live. But when you spin up to 8k+ your F'ed. It will hit.  That's why I was wondering if you ever did one this way.  Fyi minimum squish for a 500 is .040-.042 and it should be a tight engine I've seen worn ones ding ring land closed at that also every engine is a little different wear plays into a lot of the SAFE minimums for these machines.