I had a Mopar brand 2.77 low gear set installed in my old pump gas Duster, that worked well with 3.73,3.91, 4.10 and 4.30 running 315x60x15 M/T Et Street Radials and the same size ET Street bias ply tires with that 400 stroker motor with both the 4.25 stroke crank and the longer 4.300 stroke crank later
![up up](/ubbthreads/images/graemlins/custom/thumbs_up.gif)
That car ran 127.+ MPH with the Eddy RPM CNC heads and pickup to 134.+ MPH with the M.W. size Indy SR with a Indy 400-3 intake and several different 1050 CFM Holley Dominator carbs corked up with the air cleaner on using 92 octane OR pump swill from Bend
![shruggy shruggy](/ubbthreads/images/graemlins/custom/shruggy.gif)
I haven't used the TF270 heads yet and I don't know how they compare to the Indy SR M.W. heads non ported
![work work](/ubbthreads/images/graemlins/custom/work.gif)
The 4.250 stroke will move the mass a lot easier than the SB motor will with a 4.00 stroke in a SB 340 or 360 motor
![twocents twocents](/ubbthreads/images/graemlins/custom/twocents.gif)
Good luck on your new build