Your load is more than safe, no reason to pull them!
I've loaded Power Pistol under true jacketed Montana Gold projectiles (run higher pressures than plated) at 7.2 grains and 8.0 grains already. The 7.2 chronograph at 865 fps and the 8.0s chronograph at 937 fps. The 8.0 grain is .1 grain under max and is quite hot. I was loading to 1.25". They had zero pressure signs. Power Pistol is very forgiving, and you're a whole grain under max. I'd suspect you're well under max pressure and I'd bet you're right around 850 fps.
99% of the .45 ACP I load is shot through my HK USP, and it can handle the hottest loads. Your G21 should do fine with warmer loads as well. The 7.2 grain load is very close to factory/GI spec but Power Pistol is a bit slow, so it's flashy and loud. However, it is very consistent, accurate, and pretty clean burning, too.
I've since switched to plated bullets as well and have loaded up 20 for testing at 1.275" OAL and over 6.8 grains. I suspect these will be about 830 fps. Hoping to test and chrono next weekend.
In my experience plated bullets load much closer to jacketed than lead in terms of the powder / velocity relationship.
Power Pistol IS a lot of fun, and in 9mm it's really hard to beat. In .45 ACP it works well too, but it is unnecessarily flashy and loud if you just want to replicate ball ammo. I am going to look into Solo 1000, W231, American Select, or Bullseye here shortly for my more basic .45 ACP loads.
ETA: Also, in my experience plated bullets are good for well over 1000 fps. They shoot fine in my 9mm loads at 1200-1300 fps and in .357 Mag hovering right around 1300 fps.