4cyl T-5 swap in 68 mustang 302?

I'm not sure I would use a 4 cylinder T5. If your 302 is stock with a 2 bbl then it may hold up if you don't drive it hard.

Check out Modern Driveline. They have everything you need for the swap. Thats where I got my crossmember and clutch cable. You can also look at Ron Morris and Mustang Steve.
 
a 4 cylinder T5 will hold up behind a stock 302, as long as you are not power shifting on a regular basis. however first gear will be rather useless with that combination. the first gear ratio in the 4 cylinder T5 is 3.97:1. better to find a V8 T5 instead.