C-4 ????s

[sleeperstang]

I have a 65 stang with C-4 tranny. I'm not sure how c-4s, in stock form, generally perform, but mine shifts from 1st to 2nd gear almost immediately after taking off, and then shifts from 2nd to 3rd gear somewhere around 30-35 mph. To me it seems as though the shift points should come a little later as that would help catch engine at better rpms. Is it common for C-4s to be geared this way? What can I do to change this without any major modifications (in other words, is there some valve or something that can adjust this, might be dumb question, but i gotta ask)? Finally, what modifications are there that can be done (shift kits, gearing, rearend)? I plan on tuning my engine to about 350 hp when completely done, might go little higher, no more than 380 hp completely streetable with low end being my target. Thanks for any help.

Sleeperstang <-----I know, 380 hp might not let it be a sleeper no more

P.S. By the way, my budget could go as high as $350 for any tranny modifications, I do plan on putting a T-5 at a later time.