I use JSPs in my rifle. No impact data, but I am leery of driving the JHPs too fast through the Marlin. The chrono indicates some pretty impressive gains with the longer barrel.
Never shot a deer with a handgun, but would use the Federal 300 grain SWC.
How big are your deer? Here their pretty small. My hunting buddy killed several with the Eldorado Starfires and was pleased. Not sure how a 200 pound cornfed critter would react..