Would you cut 68 Form S Fish for 1 7/8 headers?

I have a 68 Form S 340 4 spd fastback. No rust, definate driver, (once the motors back in). The problem is I have 1 5/8's headers and the massaged t/a heads exhaust ports are bigger than the header flange openings creating a definate restriction. I have a new set of Heddmen hustlers 1 7/8's that has one tube over the frame. The 340 motor has 11:1 comp. hughes solid 245/250 @ 050. dur. and 560, 575 lift The afore mentioned t/a heads done by Bob Mullens for circle track use back in the late 70's or early 80's. This has to be hurting performance. The car is driven probably 2 or 3 times a week around town and hopefully will go to the strip maybe once a month. It seems to me that the cutout area could always be put back if neccesary. I don't intend to ever get rid of the car, but who ever knows? I am looking for thoughts on this. Also can't afford custom headers.