Magnum heads worth the effort?

I currently have a 1974 360 with an untouched bottom end so pistons are down the cylinder. It has X heads on it that are measured at 68cc, and an XE268 cam, early 340 exhaust manifolds,2800 stall with 3.73 rear, 26" tires. It runs great for what it is but I would like more of course. Would I get much gain with changing to fresh Magnum heads for better compression and flow? I could get a fresh set for $400. I don't want to spend the money on EQ heads for this motor,