1. Subrails: Not reproduced to my knowledge. The crossmembers are. As this is obviously pretty far gone and going to be a street rod consider making the subrails out of rectangular tubing, cut the outside to profile, weld it up, and straighten the warps.
2. Mounting on a A frame. With body blocks installed both model A and Model T basically have a flat mounting surface on the body mounting to a flat mounting surface on the frame. The body bolt hole locations are different and will have to be moved. The rear crossmember on the A frame will be taller than the T and require a little more trunk clearance, and the crossmember will be slightly too wide and will need to be trimmed with the body mount hole relocated.
The wheelbase is about 2" difference so you will have extra motor room, and if you use a hood you will need a custom extended one.
What are you going to do with the radiator and radiator shell? If you are going to use the T there will be interference with the front crossmember ahead of the spring, and the front of the frame will need to be modified. If you are going to use Model A the top of the radiator will be taller than the top of the cowl. A 4-1/2" chop 1932 is about the right profile for a T, we make fiberglass shells and Walker makes a great radiator.
What about fenders? If you use T fenders (matching to the T radiator with the above modifications) you will need custom extra length aprons and running boards. If you want to use 1929 A fenders we make fiberglass rear fenders that look like 1929 fenders yet fit the 1926-27 body. They still require special running boards and aprons but we have these available too.
I have seen a few of these done, and done right they look fine. With the wrong mix of parts they can look like a hash job.
