Whats the max bore and best years to start a 360 project, What is the min wall thickness & whats the max HP you guys have made before block failure? I have read the 71 to 73 had the same wall thickness as a 340?

Nothing is a given. The 71 blocks seem to have the aura of being thicker. But core shift tends to make that a myth. If you plan to go 4" stroke, have it sonic tested. Look for a minimum of .150" (or whatever your builder likes to see) on the major thrust and go from there. I dont like to do strokers bored further than .030 unless the block tests perfect. For stock stroke, I think .040 is the max recommended overbore. Again, sonic test to be sure if you want more.

You can always Hard-Block it to some degree to help stabilize the cylinder walls.

74 and earlier 360 blocks if sonic checked good minimal core shift should be able to go 4.100 bore I have had no problems up to 580 HP with good block prep studs top and bottom ends and know of several making 620 to 630 early and late model blocks

I have a spare 73 360 we bored .060 a few years ago it was around .195 min thrust side when we bored it, I was thinkin of goin 4.100 cause it started rustin from sitting , I got a 3.79 crank for it with h beams but no pistons , We would be looking for at least 650+ out of it with my w5s, is this too much for a stock 59*, we run studs on everything and steel main caps we try not to turn over 7500?