Hi Sapper,
SupaSwift are a great mower and a nice little Aussie company that could.
According to NormK, SS and other brand mowers beside Victa seem to use a standard axle stub diameter smaller than Victa's unique thicker axle.
The beauty of SupaSwift is they seem to use some components common to other makes. Victa front axle clips fitted on mine which had one missing. It takes Victa 18" blades as well.
You may find Rover, Masport and SS may take the same axles. Not sure there. I used a bearing out of a Sanli mower to replace the badly worn nylon sleeve on the wheel of my 1980s SS. It's a great trouper now with a vertical pull Briggs.
It's hard to turn down a mower being offered free. I just hope for the sake of your relationship you don't keep getting offers!