451 Flat tappet hydraulic cam?

I run a xe284 in mine. Its an OLD Jim Hale 451 kit that used Ford 460 Arias pistons and a 400 length rod. In my Dart it has went a best of 11.96 through the mufflers at 2300ft. Very consistant station wagon motor. Stock 440 crank,balancer,400 rods, stock rockers and shafts and ported 452s. M1 single plane with a Holley 830dp,TTI 2" headers though 3" Flowmasters. MSD distributer and Digital6 ignition. Very simple with haul the family station wagon reliability. Pistons are flat with no valve reliefs so im pretty much maxed on cam now. If I could id throw in a .580 or so lift hydraulic roller. Right now I shift at 6K and there is no need to go higher.