There's enough info around to indicate it can be done w/o much issue, & to be safe, given a good AGB like an SLR, if I were doing it, I'd likely size the gas port to the same size as a typical rifle gas port. You can always go back later & build another barrel with a more optimized port, depending on how the initial one works.
That way you can be more or less assured of having enough gas, but with the ability to dial it down as needed for more flexibility..............yes, it will (somewhat) negatively affect the gas port size life, but I don't think that's an issue.
But since you're a 3-Gunnur, I guess I'm wondering what your practical view of what you're trying to accomplish with a gun that has a 20 or 22" barrel on it compared to a 16 or 18" gun goes as far as actually shooting & competing with it goes. Given your current (pretty effective setup), I think the improvement in actual shooting perception will be negligible, but who know? And it's fun to experiment.
WOA is good & very nice to talk to & work with, but I'd highly recommend also talking to Paul Craddock too. He spent a lot of years at WOA & has a deep knowledge & experience level & a memory like a steel trap with what has been tried in the past.............he even remembered my name from doing business with WOA in the past.
Anyway, good luck & let us know how things work out.
MM