I've been suspect to running the larger GM brakes on the smaller car, so good to know about the issues. My T is a little heavier that most other Ts as it's an all steel C-Cab Delivery. Still really light by comparison with other 30s cars though.
I've talked to Speedway on a couple of occasions and they were not able to locate me kits or even just brackets to use the MII rotor/caliper setup. They suggested contacting one of their brake manufacturers to see if something could be engineered and produced. That sounded pretty expensive to me so I left that as an option B or C at this point.
Right now I'm doing research on an old '70's era disc brake swap that use to be popular on the 37-48 spindles. Guys would use mid 60s Volvo 122S front disc brake calipers and rotors along with either a spacer or custom bearing and machining along with a custom caliper bracket. Dad said he did thins swap back in '72 on is '32 Five window and it worked great. He said he ran 14" aluminum wheels and recalls the rotors to be 10 or 10.5 inches in diameter.
I commend Wilwood for putting out a kit, it's just not in my price range. I know, I shouldn't put a price on a safety item like this but I think there is still another cheaper, just as effective way. Part of being a street rodder!