the XPZ can technically be run on stock heads, but wont make any power because it wont be able to flow like the cam needs.

but yes, i would run 130# springs with ported heads.
Very true. But you have to give the vavle guides the much needed clearnce they need, then you can run the xpz on stock heads. Which would be about as dumb as a no legged man at an ass kicking contest. I'm sure you already know this. Just wanted to make sure some one doesnt get a great idea and try it out not knowing that.

I'm running custom heads with over sized vavles,130 pound comp cam springs,Low Mile Stock L36 lifter's, and a double roller timing chain with no issues at all.

The head work, springs and doube roller is all a must. If you dont have some decent heads then I wouldnt waste your time with an xpz. Save your self the work of pulling the heads at that point and just run an xp cam.