Not necessarily reliable, but Quickload calculates that with the Speer Grand Slam 285 grain bullet, 18.0 grains of AA 5744 should produce a 1500 ft/sec MV from a 24" barrel and be well within the SAAMI peak pressure limit. 20 grains takes chamber pressure to very near maximum and produces a MV of 1625 ft/sec. From experience, I have found that Quickload is optimistic when it comes to MV estimations.
I do have an older (2003) AA powder guide which provides some 5744 recipes for the .38/55:
Sierra 200 grain - 23.0 to 25.5 grains, MV = 1705 to 1853 ft/sec
Hornady 220 grain - 21.2 to 23.5 grains, MV = 1516 to 1648 ft/sec
Lead 240 grain - 19.8 to 22.0 grains, MV = 1473 to 1601 ft/sec
Barnes 255 grain - 19.4 to 21.5 grains, MV = 1277 to 1388 ft/sec
For the .32/40, same source:
Lead 170 grain (GC) - 18.0 to 20.0 grains, MV = 1658 to 1802 ft/sec
Hornady 170 grain - 18.0 to 20.0 grains, MV = 1635 to 1777 ft/sec
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Note that AA 5744 appears to be the near-ballistic twin to IMR 4227, so you might be able to find some IMR 4227 recipes that would work as well using AA 5744 instead, for both .38/55 and .32/40. IMR 4227 is very underestimated as to its utility. It is superb for use in many of the older calibers, up to .45-70, especially with lead bullets, as well as in magnum handgun loads.