Evening Pete,
Personally I would avoid the 180 SSP, even tho yours is a shorter barrel, I would think you will be able to surpass its vel range. (Unless you want to load it down.) At least if your hunting with it...
The 180 and 220 Speers are good choices as is the std Hornady 200 Spitzer.
As for the shorter barrel, remember the Win and Marlins had 20" barrels... Unless specified, its likely form that length barrel. So altho you will not find spitzer data, the vel is not gonna be as big a difference as you would expect for a std caliber used in a 22-24" barrel. As for spitzer data, simply start at the starting load or even 10% under and work up.
The 225g bullets, I would go carefully looking at 250 and 200g data and find a starting point drop another 10% and begin. Choose a powder middle of the road, maybe even form a source that lists pressures they got.
I will see what I can find for data, maybe I have some you have not seen...
CW