To me, "stall speed" is a variable "black science" of sorts. Reason? A 727 with an appropriate torquc converter for a Slant 6 will stall at one rpm level. Yet when that same torque converter is put behind a 383/335, it will stall in the 2300rpm range, and a bit higher when behind a 426HEMI. Just because there is more power in front of the converter.
A side dynamic is that you WANT the engine cruise rpm to be above the actual stall speed, so that the converter "slip" is minimized at those highway rpm levels (which means less heat in the ATF, too!). Note: unless the torque converter is a lock-up design, there will always be a small bit of slip at cruise rpms (like up to 5% or so?), which is normal. AND this tends to relate to your rear axle choice with the GV OD unit. As with the 3.55 in OD, the effective rear axle ratio is approx 2.50. You can tell when the torque converter is "tight" as throttle response will get very accurate when that happens, whereas just a few mph lower and the throttle response will be more soggy. For example . . . on my '70 Monaco Brougham with the factory 383 "N" 4bbl V-8 (3.23 axle ratio, P225/75R-15 tires, 25mph/1000rpm, factory cast iron intake, stock 4734S (replaced the orig 4732S) AVS, stock distributor, smaller diameter factory torque converter, stock 256/260 cam, factory dual exhaust), at 60mph on the highway, throttle response is a bit soggy, but at and past 62mph, the response to small inputs is very responsive, by comparison.
Another side dynamic is how the torque converter "loads" the engine at 700rpm hot base idle. How the intake manifold vacuum changes between "P", "N", and "D", for example. A too tight of a converter will put too much load on the engine and lower the idle intake manifold vacuum to less than 10"Hg, which can trigger initial power valve circuits for additional enrichment. Not good!
So, IF you "size" the converter to match the cam and such, that can be good. BUT with the GV OD unit engaged on the highway, the converter might not be past the lowest rpm level for good operation. In which case going to a 3.91 or 4.10 axle ratio might be advised.
Just some thoughts,
CBODY67