i DO NOT dispute what Ed says for one minute about the .125 boring..and i strongly recommend no more than .100..
HOWEVER...
I personally have and run a 454 passenger block with a 4.25 stroke and a 4.375 bore (511ci) ..and have no problems..this is .125 over by the way.
i have been told it would split,run hot...you name it i was told.....i realize its running on the ragged edge and its best not to go that far for insurance purposes...BUT i wanted to say it can and is done..i am proof of this..it may go boom tommrrow..but for now it runs great,,,good oil pressure, Sunday i made back to back passes in 82 degree heat and it never got above 185 degree's..
also i Do NOT run NOS but i do have 14 to 1 compression and about to convert to alcohol..
by the way my block is the 512 series.....
Note'- if it ever goes boom..i will not bore that large in future..
Brian
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Bjuice..
"I'M YOUR HUCKLEBERRY ! "