Straight six, this won’t mater. If using headers and you have power steering there may be a clearance issue with one of the runners contacting the adjustment screw on top of steering box. A shim under the left motor mount or a ballpeen hammer corrects that issue.
Stock pistons stay well below block deck height on a slant, making it a noninterference engine. Removing up to 0.100” from factory dimensions form head or block is about the limit before having to use custom length push rods.
My understanding is that removing material from the block is preferable to shaving head on these engines due to how far down stock pistons reside in their bore at top dead center.
Before you pull a cut depth out of thin air, you need to pull the head, measure what you have, and utilize a compression ratio calculator to design a configuration that keeps dynamic compression ratio in line with pump gas use.
