Are the 55-58 Blocks as thick cylinder walled as the 59 389 ?
 

Just curious if anyone knows the overbore potential on early 55 -58 blocks vs the better known 59 389 being the thickest strongest ones.

Back in 1961 I bored a '57 block 3/16" over and ran it thousands of miles as a Tri-Power 381 c.i. But in recent years, with wall thickness measuring available, a couple of '58 blocks were only safe thicknesses at 1/16" overbore. I guess I was just very lucky with the '57.

Thanks for that Jack , eventually I should acquire a 56 317 and HD 3 spd from a buddy's Chieftan and may use one day for some kind of rat rod hot rod idea and that trans is suppose to be super strong too but thought at minimum bore the 317 to 4.0 so its right at a 327 with the 3.25 stock crank but more is always better if there is a weird stock piston long rod odd ball combo that could be done as well I was trying to figure out if a long rod combo with a 301 piston could be done as well I have spare 9.3 housing that has leaf perches on it for a 55-59 pick up