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A four speed manual 289/302/351 car would work to. It's probably the same bell.

Good luck on the search.

I would stick to the 157T bells. You'll need a much smaller hammer. A 10.5" clutch will be more than enough behind a 250 in such a light car.

Back to bell housings. You can also use a stock 250 bell or a four speed bell from a 289/302/351W. You would then just need the T5 adapter plate.
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The 351W uses the same bolt pattern as a six bolt 289, and 302. As long as the pivot is right and the depth is okay it should work.

Wilwood has a universal pull style slave that you could use....

I agree. It looks kinda funny. I have a friend with one in a 69 Mustang. It has a nice feel.

I don't think you will have a problem fitting the master. They are quite small.

A hydraulic clutch would be nice. You could also get one of the cable clutch kits from the website I posted earlier.

I've heard of people using Mazda clutch masters. I'm not sure what model. Maybe...

These guys should have something.

http://www.moderndriveline.com/

You could probably source one from a T5 equipped 5.0 Mustang.

Ford did have a brief period of zero balance 302s. They went from 28 to 0 and then to 50. I'm no expert on the 250 six but if a standard small block V8 flywheel fits, you can buy a new zero balance...