Tried to put my $.02 in earlier but my computer crashed. Our setups are very similar. I'm running 21# accel injectors @ 37.5#. I could've got by with 19# but since I was buying new I figured I'd allow the extra margin for improvements. What condition are your injectors? new, used, leaking by? Planning on a dyno run in October with wideband O2. If you want, I could let you know how it turns out with my A/F ratio.
Saw a supercharged 91 on a chassis dyno last week gain 31 ftlb & 17 hp (AT the wheels) just by reducing fuel flow. He didn't have an adjustable regulator and he could only do so much with his FMU. 1st run his A/F ratio went off the scale low (super rich) as soon as they put the pedal down. 2nd run his A/F ratio held where it should for an extra 1200rpm then it slammed off the scale low. 3rd run...I didn't hang around to see since he couldn't make any other adjustments. If you don't have a dyno, then you just have to play the test & tune game.
Check out Accel's site at
www.mrgasket.com , they've got some pretty technical info on their injectors. Maybe it'll help you figure out which direction to go.