I have only been repairing these type of mowers for about 40 years and I have never used a puller to remove the boss on a Victa. The Victa boss is usually on a taper unless it is a 4 stroke engine mounted on the frame.
If you get it off with the puller let me know as I would like to know the brand that you use.
Regards,
Bruce
Please do not PM me asking for support. Post on the forums as it helps all members not just the individual.