If the engine has sufficient torque the stall speed in the 1600-1800 range would pull better gear to gear and reduce transmission temps. If you have a hotter than stock cam and just use the Van to bomb around in, the increased stall speed would give you more oompf off the line and increase the...
Yes, you could use the B&M flexplate for the 360 and that would solve the balance problem but not the increased stall speed issue. I would consider purchasing the correct converter for the application and using the one you have for something not requiring a weight but needing the increased stall...
To act like what you are describing the converter would either have to be extremely modified or badly damaged, unless your trans is starting off in a higher gear instead of first. You should have noticed a bad enough engine shake to make the stall speed seem secondary if you installed a non...
A 1975 360 will have a converter with a large triangular weight welded between two of the mounting pads. How are you determining that it has more stall speed than it should?
Big Block motor homes had 4 pinion planetary set, 4 clutch high drum, and high strength input shaft identified with yellow paint mark and groove cut into the spline area.
Check the reverse boost valve to be sure it is free, check that there isn't a checkball restricting the separator plate feed hole for reverse. You can actually leave the check ball out of that part of the casting for more reverse apply oil.
What a cool discovery! We have the remnants of an old dump on our place and it pushes colored glass and pottery fragments to the surface sometimes, but never an intact bottle and certainly never something as old as your find.