What is the general application of the car?
Bracket Drag racing and city driving then the C-4. A C-4 and low gears like 4.10s will not be a pleasant highway car at all.
General all around driving including highway and bracket drag racing then a WELL built AOD would be a better choice, especially w/4.10 gears. OD is great to have in daily driver.
I won't drag a t-5 for bracket racing as personally, I'm not good enough at perfect shifting, I prefer auto's for bracketing. They are the most fun for sure, and put the power down in a great way. Nothing like slammin through the gears in a strong manual car. Seen lots go south under duress though.
Think about an AODE/4R70W and the Baumann or Hughes controller. Nothing come close in the automatic world. Have your cake and eat it too. Drawback, expensive outlay, well worth every cent IMO.