Finishing underfloor of NON Restoration ?????

[CamarosRus]

My current project is a 73 R/S LT CAMARO.....This car will have a very good restored
"look" but not a trailer queen 100% restoration !!!!!. This is a very good quality "driver"

Norwood built with Red Oxide on underfloor......where light/moderate rubberized undercoating was applied at dealer (??) when new (??).

Body Shell is on cart. I used 4000psi pressure washer to clean bottom of shell. Areas of undercoat. My original thoughts were to use UPOL "RAPTOR" on underfloor/wheelhouse......but now questioning how RAPTOR would adhere over areas of
undercoat and areas of Red Oxide metal ?????

My question is what BEST new undercoat should I apply ON TOP of existing undercoat
Aerosol Cans of what brand OR the 3m Body Schutz with the can top "gun" ????

Thanks for your opinions and 1st hand experience ????