Excluding any diesel oils, for conventional, I think you're pretty limited, especially if looking for something with detergents for street use or that doesn't have too much Zinc. I know for 20w50 when I researched recently I only came across three conventional oils that had higher levels of Zinc / Phosphorous versus what most of the 'regular' oils have (~800?ppm give or take?)
For conventional, gasoline 10w30, I think you might be down to:
Valvoline VR1 racing oil 10w30 conventional, 'recommended' for street use if no cat. converter, Zinc 1400 ppm, Phosphorous 1300 ppm
Also there is:
Lucas Hot Rod & Classic Car Motor Oil 10w30, Zinc 2100 ppm, and 0.19 Wt% phosphorus
Lucas Hot Rod & Classic Car Motor Oil SAE 10W-30 is manufactured with the highest quality paraffinic base oils and is fortified with a unique additive package containing high levels of zinc, molybdenum and phosphorus, which provides a tougher, thicker additive film for maximum protection even un...
I don't know if this is a concern for your engine, but for my car (SOHC) I would worry about that 2100 Zinc level being too high. Also specifically states, 'Not recommended for passenger car use', I don't know how much you will drive the car and if you need a strong detergent pack
FYI's Lucas' 'regular' conventional 10w30 has 861 ppm Zinc.
Kendall, which is an option for me with 20w50, doesn't make a conventional higher zinc 10w30 (at least per their website). Neither does Motul, which advertises a higher ZDDP conventional for 20w50, but in any case their tech. sheet didn't list the specific ZDDP level
Most of the higher zinc oils I found, for classics, hot rods, racing, etc, were syn or syn blend (Penngrade notably being a partial syn). The AMS oil recommended above is synthetic, to be clear.
FYI, the current Valvoline regular 10w30 conventional, Daily Protection, has 760 ppm Zinc, and 690 ppm Phosphorous
I can't speak to the other questions such as conventional vs syn