A quick update:
started with conservative loads under the 165gr .321 projectile (for the .32 WCF or .32-40), just to be on the safe side.
Grouping with that bullet was a bit discouraging but pressure seemed low enough, so today I tried a series loaded with 150gr .323 Sierras.

Using 40 to 45gr AR2208 (Varget) all loads managed 2-inch groups or slightly better at 50 metres.

That's good enough with the original iron sights to pursue the matter further.

More to follow....