IMHO, load development is going to demand a chrono. A chrono will be one of the only ways to accurately monitor chamber pressure, which is extremely important for your safety.
I say this because a lot of the handguns using this cartridge were made before 1) steels were pressure tested and 2) using modern metal alloys, which helped usher in the age of 38Special and 357Mag chamber pressures.
• • One should also NOT assume that modern black powder replacements, commonly used in Cowboy Action Shooting, run at the necessary lower chambers of Black Powder. These are powders such as Trail Boss, Tin Star and similar. These are modern smokeless powders and as such run at the same high pressures as the powders you already have on hand.
Depending upon the age of your handgun, you may want to consult the specialty antique handgun forums for more concise information.
Hope this helps.