Radiators: Is 22" enough for 400 HP?

I have a 22" radiator in a 408 - 69 Valiant. - H.P. is around 450 - 2 row alum rad - 1" tubes - shroud - 7 blade Mopar fan - And overdrive on the fan/water pump ( larger crank pulley - smaller water pump pulley). Cools, marginally, with 50-50 anti freeze & water. - If you need more cooling then run just water with some lube like Lucas or _____. That should be your choice in Ca. i.e., no anti freeze.