I am in line with Juice on this also, it can be bored that much, the key is to have it sonic checked and mapped out for sure, that way you have no doubt what the status of the block is as far as any core shift, many had shift also.
I run a 427 tall deck truck block, .100 over and a 4.25 stroke, and get this (6.800 long rods :shock
and it makes it almost like a 427 as far as the rod ratio goes which is 1.62 and mine is a 1.60, and I run my engine to 8000 rpm's and run 9's in a 3728lb. Elcamino and the cuin is a 505. It runs like a pissed off weasel for sure and man does it pull hard and launch too
I have obtained a block from a guy in Ohio also, brand new made for Bluebird bus company that has thicker walls for more bore jobs in there bus's, and well, they went to diesel and many were for sale, and let me tell ya, mucho bore on my block. It is a GM block also 427 style, but with thicker bores, that's all.
And Ed is darn near 100% right as almost all 427's were either pass car blocks of the 9.8 deck heigth, or, the Marine/Truck tall deck 10.2 version installed in many trucks, boats, buses, motor homes, and others. as well as 366 blocks that are good for anchors
My 2 cents worth.
Elkyman
John