You really only need the 240 grit belt for maintaining an edge, or if like me you just want to spend the money get the diamond belt, only had mine 4 months so far, but I know of at least one professional turner who has had the same diamond belt on for 4 years, So actually not expensive over time.
The required piece is the long grind (3 position)
https://www.yandles.co.uk/robert-sorby-proedge-long-grind-jig/p5748 jig. No need to change the factory angle on the holding part of the jig. in fact it is best if you don't. Note Yandles are not the only supplier, I just used them for the picture!
Just remember that the ProSet angle is for the first hole, add 5° for second and again for 3rd. So to get a 45° on your spindle gouge set the length to 35° angle on the ProSet, then use the 3rd hole = 45°,
Personally I don't like the wing on my spindle gouges to be so long so use the first hole for them, and coincidently I like a long grind on the bowl gouge and a 55° angle so I just use the same length setting on everything. Though recently I have been playing with Stuart Batty's 40/40 grind and have modified my ProEdge so I can produce that.
https://robert-sorby.freeforums.net/thread/207/stuart-me