Primary oil change - stripped a torx

Yea I stripped one of the torx heads to day changing primary. I adjusted clutch a year or 2 ago, and foolishly thought the derby cover was allen bolts..Sucks getting old and hard to see, so I set motion todays failure by buggering the tox back then. I was able to get clutch adjusted and knew I would be in trouble in future. Future was today. Used mini grinder to score a straight across slot to get torx out. Question - are there better derby bolts out there, hex head or deeper allen? At least I was able to get 2 of the 3 holes changed today, primary and main oil. Tranny in near future. Another rant, have the Rineharts, WTF were the designers thinking on that rear down pipe, impossible to get to oil and tranny filler..May be time for new set of pipes as well.