I am working on my own 8HP70 swap into my 67 Cougar. I was using the 5th gen Camaro starter. Well, that starter has a unique nose on it and it does not work well with the Domiworks adapter. I recall having a similar clearance issue when I used that starter with a stock T56 bellhousing. Instead of butchering the adapter (more than I already did) I ordered this truck starter. It has a different nose, but still have the connector for the solenoid wire.
You can see where I have already clearanced the adapter, but had I used this starter from the beginning, that would not have been necessary.
The other difference with this starter is that it does not have provisions for the heat shield, like the one that is used on the 5th gen Camaro starter. I don't think this will present any issues.
This shows how much the bellhousing has to be notched in order to clear the nose of the starter. I could have done a slightly smaller notch, but I didn't want to keep messing with it.
I plan to 3D scan that area and have a small cover designed and 3D printed. The engine swap party is a little over 2 weeks away.
Andrew