RE: Small, broken drills in aluminum...
When drilling the key is to use low speed, plenty of coolant (keep the pressure on to avoid skidding and work hardening on S/S).
I recall breaking a tap in a 1/2" thick stainless steel pipe flange. Obviously it was the last hole of the six. I marked it out again between the original holes after welding up the mistakes.
Works with S/S but when a colleague did the same on an Aluminium component that had to be Anodized the mistake became obvious.
Will your adaptor take double the number of holes?
Best of luck!!
old git - - - - - aka John L
WACO Brotherhood No. 14.