Great! Now throw those drill bits and that instruction sheet in the nearest circular file, and do your best to forget you ever read about altering the plate!
There is a method that I've used to beef up automatic transmission clutch assemblies by machining them to accommodate a thicker stack of friction and steel plates, which has the effect of adding to the swept area of the clutch. It's the equivalent of installing a larger diameter clutch disc ahead of a manual transmission. Then, even with stock shift timing and no increase in line pressure, the clutch is able to carry much more load. I've done that mostly on rigs that tow heavy trailers, but it also works well on high-HP hot rods.
Jerry
