My 390 Holley runs a 52 primary jet, and .028" PVCR holes.
It has won numerous carb shootouts with the GTECH on bone stock 250 and 292 engines. I'd try 54 jets 1st if it had headers/cam but for now I think its gotta be near perfect.
For full throttle you need to know both the jet size and the PVCR hole size. I never even remember the vacuum rating ie 6.5 or 8.5 etc but I always measure those holes in the metering blocks. Don't know why Holley doesn't list those.
Glad the mix screws seemed to help. I also find that due to crud in the gas, you can set them, then suddenly after sitting for a year it will be "way too lean", cuz dried gas crud is clogging things up. you can turn the mix screws out as a crutch but that's a hint that the carb is dirty inside.
