At what HP/Tq?

i am finally back from overseas and will have a garage again in a month or so. I am finally going to have the time to put the 6.1 I have in my Barracuda. I currently have an open 3.55 that has to go. I am on the fence about throwing a Dana in. At what Tq level should I ditch the thought of an 8 3/4? 6.1 is currently stock. Will have headers and a tune. MAY go Kenne Belle down the road, but that will be a while I think.

Car will be street, occasional track.
17 inch tires
Rebuilt 46RH


Thanks