The only difference between a standard PF30 frame and Cannondale’s PF
30a frame is 5mm of extra frame width to the non drive side. So quite simply all you need to do to counter the problem is offset the extra 5mm from the non drive side cup.
A machine shop would easily be able to do this if you don’t have access to a lathe.
Step 1: Machine 5mm from the face of the non drive side cup to make 19.0mm length.
Step 2: Bore the 37mm internal diameter to 11.95mm deep. ( This will completely remove the original bearing seat and match up with the far edge of the internal grove.)
Step 3: Because you’ve had to bore the hole out an extra 2.7mm you’ll have to machine a small spacer as drawn.
To keep accuracy, when the washer is inserted the distance from the face of the cup and the washer should be 9.25mm. I used a surface table and some emery paper to take up any machining tolerances.