Twist doesn't change with barrel length, only with your intended bullets bearing surface (which is often linked to weight as heavier bullets generally have longer bearing surfaces).

Personally, I had a Magnum (Heavy Sporter) contour in SS with a 10" twist and 22" long. It was great and shot well. I ended up selling it Frank since I wasn't shooting it as much as my 308 and he reports great accuracy and velocity results.

If I had it to do over again and I was looking at 22" length, I think I would go with a Varmint Contour and get it aggressively fluted, and of course thread the muzzle with a protector in case I wanna add a brake or can later.