Lost reverse, need help finding it. 727

What is the rest of your combo.
What stall is the converter you have.
Is that their 11" converter

No, it's classified as a 10". but Paul @ Turbo Action will tell you, it's actually a 10 1/2"
It flashes in the 4200 rpm range, but it only has about 5% loss. Yours is roughly 15% that's why your trap speed is down. just not coupled good. You could expect as much as 4 tenths and 4 mph with the right converter. seen it happen before.
My combo? 3140# Dart, 12.34 CR 360, ported procomps, W5 int, .638/.656, 255/260 .050 solid, self done 650dp, ( trying to get a 950 working now) Dougs 450 headers, 3" Exh, 904, MRVB, TA 10", 4.11's/spool, MT 295's
last pass: 11.103 @ 121.52 and an abysmal 1.6 60'. at 1625 DA
I've got a Lupo 9 1/2 in now. I'm looking forward to my next time slip.