# 6 spark plug access hole Big Block

U wouldn't need to get the hole perfect in line, just close enough to get in there with a wobbly extension and a socket. You could cut the hole just a little bigger than the extension then put the socket on in the engine bay, if you're worried about making a big hole .
Making a small hole is not going to effect anything structural, matter of fact I'm removing my inner fenderwells completely but will be replacing that rigidity with my roll cage bars to the front frame.