There is plenty of clearance for what you suggest, and not a bad idea should I do it again, but I would probably tap the plate and thread the screws in from the back rather than countersink. Clearance at the back side is pretty tight. As far as chain adjustment, the amount of travel is surprisingly small at the mainshaft. I took over an inch of play out of the primary chain without any noticeable distortion or cracking of the RTV. I considered bonding a gasket to the inner steel plate but figured it would eventually oil soak and weep/seep/spew-whatever the proper term, and cause me to go in again. At least with RTV all I have to do is pull the clutch and give it another smear rather than pull the entire cover.