Jack: My Lyman 43rd shows only 77 and 84 gn cast bullets for the 32 S&W, with Red Dot charges running from 1.4 gns to 1.9 (accuracy load) for the 77 gn slug and 1.3 - 1.7 gns for the 84 gn slug. Unique charges run from 1.6 to 2.6 gns for the 77 gn slug and 1.5 - 2.5 gns for the 84 gn slug.
I would suggest that if you were going to use a 100 gn slug you may wish to start or stay in the range of 1.2 - 1.5 gn of Red Dot or 1.2 - 2.2 for Unique.
Also, please understand this is a old and slow cartridge. Accuracy loads for the 77 gn slug with 1.9 of Red Dot run to about 730-735, while the accuracy loads with the 84 gn slug using 1 gn of Bullseye, run to only 440'/sec. HTH.