I'd do the head swap and see what that gains you. If you still need a little more ET I'd get a better/looser convertor. When my car ran 7.0-7.1s my 60ft was typically 1.51-1.53. I don't think you'd seen a big improvement from 1 7/8 to 2" headers. I went from 1 3/4" TTI to 2" hooker fenderwell and I might've picked up a tenth if I"m lucky in the 1/4. I have a .040 440 10.9:1 MP .557 cam, Trick Flow 240, Victor Intake, Proform 850, 727 with 5000 stall 8", Dana 4.56 using a 30" tire. Car weights 3200lbs with me in it. Best it's been is 10.49 @ 126, but typically a 10.60s car.
2' hooker fenderwells are about the worst hp header out there, primaries are too long and mis-shapen, collectors are garbage too. If a header has a bolt flange around the end of the collector it is designed for street use. In other words, hp is not the primary concern. Getting the exhaust attached to the head is.
Using those as a comparison to a 1 7/8 tti isn't a good one in my opinion.
