Just a small update:
I've continued to try a few different hunting-appropriate loads. Right now, I'm using quite a bit of AA powders since that what I have most of.
Shooting the Python from a rest at paper at 25 yards with upper-level charges of AA-7 have observed the following. (And no, I'm not a caliper-carrying group measurer....

)
The Everglades brand 'bulk' 158 gr. JHP did very well - about about 3.5 inches. I'm sure it could be better - as usual the real issue is the nut behind the backstrap.
The Hornady 158 gr XTP did just a little better - closer to 3"- 3.25".
Had some factory ammo by Speer, not sure if it's made anymore - 170 gr. DCSP (Dual Core Soft Point). Large meplat and actually made for hunting. It did much the same as the previous 158's, about 3"-3.5". Recoil was not as stout as I predicted.
Real surprise came with the GT Bullets cast 160 LSWC-HP. It hovered around 2.25 inches consistently, with no signs of leading.
Using that bullet, I hit 6" steel plates consistently at ~50 yards.
I was initially dubious about this load because the bullet had to be crimped over the driving band shoulder. Crimping in the normal crimp groove made the COAL too much for the Python's chamber/cylinder. I also reduced the powder charge a bit to account for decreased powder space.
So, my scientific assessment: this Python was made in 1979.
Elmer K. was still alive in 1979.
Therefore, the Python obviously prefers Keith-type LSWC's.
There..... - I'm a ballistician.
Back to reality, I do believe any of these bullets would work for the intended purpose - small - to- medium Whitetails (avg. 120 lbs) at the ranges I encounter.
Thanks to all. I'll probably continue to pick away at this in an attempt to get even better groups with some load adjustment. For now - I'd settle on that 160 gr LSWC-HP.