Might buy a 340 block...

I've never seen that.

Also, the number of blocks I've sonic tested (just Chrysler stuff) is well in the hundreds and I've seen two, maybe three of those 360 blocks with bore that thick.

I've never seen any passenger car block ever with thicker main webs and pan rails.

Well I have faith that mine is gonna be on of them! Lol

I built a 360 in the 90s with a 71 block out of a 71 Newport and it did sonic test on the high side but cant recall the number.