74 Dart 360 Sport

Going to rejet my 850 Holley Install the O2 sensor and see where I'm at. Reading plugs is not fun rather get a definitive on that. Pretty happy overall I just want to run as clean as possible and not leave power on the table. At one point I did have a single back fire couple times sorted out quickly and fired up. I will replace the powervalves even though it has the protection built in concerned it may have caused an issue. I plan to go jet 76 in front and 86 in back right now they are 86 front and 93 for the jets. I think that is overkill right now and would perform better but want to be sure and get that mixture reading from the gauge. At idle I noticed it has a tendency to idle up after stopping and parked not sure if this is the valve secondary on distributor maybe to advanced? It is not dumping gas like a bad power valve or to much idle screw. I'm at 18 degrees on number one TDC no vacuum hooked up idles at 800 to 890 comfortably. Below that with this cam its kind of ugly when put in gear and without secondary even worse I need that for street. Just need to get it adjusted correctly very close now just dialing in so I can leave it the hell alone! I did try driving without vacuum advance and was simply not good experience in neighborhood and stops in traffic.