Having done a 416 stroker strictly for street driving, your numbers do sound low. You have a larger cam, carb, rocker ratio than my build. Take a look at my build and maybe something comes to mind... Like the heads? Good luck!
I updated this with a new link to YouTube for the dyno test: And here are the full specs:
Finished a 416 stroker last month and made a little video. Thought you guys would be interested also. This is a 100% street motor so I told engine builder to build it for low RPM driving. I wanted a decent idle and lots of grunt under partial acceleration. 340 block 30 over, Trick Flow 190’s no extra work, Scat rotating assembly, RPM Air Gap, Harland Sharp Roller Rockers 1.5, MSD RTR, 750 Holley Vac Secondary, Icon IC 745 pistons, final compression 10.1. He had a Comp Cams Mutha Thumpr (.522 In, .509 Ex, 235 In, 249 Ex, 107 sep) on the shelf so we decided to try that. I know it gets a lot of negative vibes and I felt that way till I saw that Joe Sherman had used them and was impressed. I asked the builder (Bill @ RAM Engineering) what he thought when we ran and he said he was surprised too; the numbers were respectable. The idle is noticeable but as soon as the RPM comes off idle, it smooths out quick and we were making 400 ft lbs torque at 2000 RPM. 524 ft lbs at 4600 RPM. 503 HP at 5700 RPM. Should be a fun driver when installed in my 3200 pound Duster.