Frankly, I think it's running pretty well for what it is. The biggest issue I see is mild 302-sized components on a 336. When I ran a 306/TW 170 heads/ TF Street Intake and Lunati 51014, I think the best I managed was a 12.6 at 106 - probably 100-200 lbs heavier than you or more. I wouldn't mess with the converter at this point. I'd put a different intake on it and see what happens. I don't think I've ever recommended one, but your car is screaming for a Holley Systemax EFI intake. That cam isn't the greatest choice, either. Cam+intake will possibly get you high 11's with your current converter/gears. Giving the heads even a good tootsie roll job is worth about 15 cfm. That's not something I heard, that's something I did and then paid to flow them.
Do all 3, and get it down to about 2,900 lbs and you might tickle high 10's.
'84 LTD LX - 9.83 at 140.09. Whippled 365 SBF with a glide and 3.08 gears. Driven to and from the track 60 miles without even changing tire pressure.