I was able to buy a M31 S&W with a 3.25" barrel. This is a solid frame revolver, yours is a top break.
I looked through my reloading manuals and did not find much information on the 98 grain bullet and the 32 S&W Long. If there was data, it was with Bullseye.
The bullets I used were commercial cast, and were two grain heavier than 98 grains, however I believe the difference is inconsequential. These were a round nose with a flattened tip.
I chronographed factory ammunition as a guide. Aquila was a mild load.
I found factory equivalent ammunition (2.25 grs Bullseye) to be so mild that after shooting 1000 rounds of it, I shot 1000 rounds of 2.5 grains Bullseye. Nothing evil happened to my pistol but I believe this is too hot for a top break revolver.
Three grains of Bullseye produced a sharp recoil in my revolver. While cases fell out, I just did not want to deal with the recoil.
Unique had potential, but I found that Bullseye worked good enough.
S&W No. 3 Hand Ejector 3.25" barrel
98 LRN Aguila Factory
19-Mar-06 T = 51 °F
Ave Vel = 665.9
Std Dev = 17.52
ES = 69.38
High = 697
Low = 627.6
N = 32
Horrible leading.
100 gr LBBFP .313" 2.25 grs Bullseye SS Brass WSP
19-Mar-06 T = 51 °F
Ave Vel = 693.3
Std Dev = 20.71
ES = 103.9
High = 721.8
Low = 617.9
N = 32
Elevation good, Windage left, Mild recoil
100 gr LBBFP .313" 2.5 grs Bullseye SS Brass WSP
19-Mar-06 T = 51 °F
Ave Vel = 768.2
Std Dev = 16.97
ES = 62.06
High = 807.3
Low = 745.3
N = 17
Elevation good, Windage good, Mild recoil, prefer this to 2.25 grain load
100gr LBBFP.313" 3.0 grs Bullseye WSP R-P brass
4-Feb-06 T = 44 °F
Ave Vel = 861
Std Dev = 14.83
ES = 57.83
High = 889.6
Low = 832.1
N = 31
no leading, easy extraction, rounded primers, sharp recoil
100 gr LBBFP .313" 2.9 grs Unique SS Brass WSP
19-Mar-06 T = 51 °F
Ave Vel = 717.4
Std Dev = 42.33
ES = 144
High = 789.3
Low = 645.3
N = 18
Elevation good, Windage good, Mild recoil accurate
78 LRN .312" 2.0 grs Bullseye CCI 500 Aguila brass
19 Mar 06 T = 51 °F
Ave Vel = 611.7
Std Dev = 42.69
ES = 146.9
High = 699.3
Low = 552.4
N = 20