The T5 is an excellent choice for the 6 cyl engine. The extra gears really help with the narrow power band of the 200 engine and make it much more fun to drive. BTW find a new shop, no excuse they couldn’t solve the leak.
You need to find out a little about your engine to proceed. Earlier 6 cylinders used 5 bolts to attach the bell housing. Later engines were changed to use the same 6 bolt set up as the V8. That will determine which bell housing and clutch set up you need. You will want to find a T5 from a Fox body (79 -93) Mustang. The T5s are classified by a major design change that added friction clutches and other modifucations to handle more power. The newer T5s are called “World Class” and the earlier are “Non-World Class”. For your application either will work fine. Do not get a T5 from another car as it will likely not fit.