I wish I had an answer
The Victor is one of the all time great pistols. I have impressed more people with my shooting abilities with my Victor. I myself only have the two original mags and a couple crummy knock off mags that don't work. I am not an expert on High Standard mags but I would think any original mag for a HS with a military grip would work. The originals all seem to have the bright green plastic follower. The only two ideas I can come up with would be to search gunbroker.com, gunsamerica.com, etc. The second idea is to try the new (well not so new now) HS Co. based in Houston. Their reputation has not been so good but worth buying one to see how it works. One last idea. It seems to me some of the competetive shooting suppliers such as Creedmoor Sports or Champion Shooter Supplies carry Victors from the new Houston, TX HS company. May be worth doing a search for their website and call them up and see what they have to say. I would try my option #3 first. Good luck. I may start looking myself as I would feel better if I had 3-4more.
Brazos