If you can get your rifling cut to any specs, and you intend on using a particular weight for the most part, then what I do is use the twist rate formula. It's pretty simple, just search for that in google or wikipedia. If you intend on using a certain brand and weight, it may be good to also call the bullet maker and ask them what they have best results with too.
That'll theoretically optimize it to the weight (the formula uses geometry, but you'll determine the geometry of the bullet by choosing the weight you intend on shooting and measuring that with calipers). It'll give you a good hard number to work with. Just know from experience, that some bullets of different weights work just as well, while some of the optimized weight may not work well at all. So it isn't a catch all, solve all, but it is a good place to start. In physics, we'd start with that, and then run tests to collect data that may point to a tweak in the twist rate, for example.
The formula works with just about any, if not any, small arm out there. Even if you go by anecdotal evidence as above (which with shooting isn't such a bad thing really, since the science of it has so many variables as outlined by the physics experiments we'd run) it's still good to know what number is theoretically optimum, and you do know that you want to be somewhere around that number, give or take.
Cut rifling may give you the most latitude with selection of custom twist rates due to the process. I like 'em for other reasons too, but that's certainly one of them. Good luck with your barrel!
