I load with SPP: CCI, WIN, and FED
1.10" is pretty short, the longer you load, the less pressure you'll get a the same PF. I've found my stock CZ chambers can load as long as 1.170" with round nosed plated bullets. WAC is about the fastest powder I would use for 9 major, I usually use SP2 (similar to 3N38); since you're in Australia, you should have access to SP2 right? HS6 is my second favorite.
Since I prefer 115s (I know the minimum bullet weight for IPSC Open major is 120 ) I've only ever chrono'd one WAC load with 124s: 7.3gr of WAC under a 124gr Xtreme plated RN @ 1.170" made 177pf through my 5.1" CZ barrel w/o holes. I've found these barrels to be significantly faster than my 2011 barrels: Schumann, KKM, and STI. Coated bullets should chrono faster and you should get more velocity at your shorter OAL, so I suspect your 6.2gr load might chrono ~160 PF.