I say not horrible because I've seen a stuck injector cause a reading over 10k. A friend had a car with a kjetronic that was slightly out, and read 3600. We adjusted idle mix from 12.3 to 13.7 and it cleaned up to under 400.
For a cammed small block, 900 isn't that bad IMO. It'll need leaned way out, but it'll probably run there. I'd try it with a nominal idle timing. Too much advance will push up the nox, not enough will increase CO.
I don't see a nox reading, so I might be inclined to keep it at 20 and just lean to max rpm, then lower the idle as much as it can be while happy. I'd also make sure the pcv is good and maybe even cheat by letting it suck clean air...