I think you really just need some minor tweaking. Honestly at 3150 lbs you should be able to run the number even with the 906 heads.

Here is an Example( yeah I know aluminum heads but we are 500lbs more and these aren't that much of an improvement over the 906)
72 Cuda 3650 lbs
Eddy heads 10.5 comp
Comp cam Number:XS282S
Duration at .50 is 244 and 252
Lift .52 and 5.4
Performer intake w/ 950 holley
Headers are Comps 1 7/8 with mufflers
Auto with 4200 stall
4.10 gears with spool
15x29.5x9 slicks
Car runs right where you are now shifting at 5400 rpm and 500lbs heavier
Oh it also runs power brakes

If this was my car I would get a better converter with more stall, we like PTC, change out the 488's. I would ditch the intake. Not a fan, if I remember right cylinders 3,5,2 and,4 are fairly restricted due to how intake bolt access was cast. Also add a 4150 carb. When footbraking we have had real good luck with the 950. I just don't see the need for the dominater.

See where that gets you. If not where you want then change the heads. I think you can get where you want pretty easily