The X cam has 2* less duration than what you have now and the Z cam has only 2* more duration, but both cams have another 30-40 thousandths lift. Don't expect much, if any, of an idle change. Also you would be going from 114* LCA to 112* LCA. This means that the idle quality will change just a tad (perhaps not perceptable) and your engine's power ratings will peak a little more and not have as flat curves, but not as peaky as say a cam with 108* LCA.
I don't think you are going to get what you want out of these cams. If you are looking for something that is made for mid and upper RPM power you should be looking at cams with longer duration, like 240* @ .050" or more. Also, if you are going to go for a high reving engine with top end power you will need to put in higher compression pistons to go with the longer duration cam. As you go longer in duration you bleed off compression and the engine becomes a dog. You need higher compression pistons to make up for this.
When you go with this longer duration cam you will also need an induction system that can feed the hungry cylinders quickly. This means matching everything else to your engine.
Without going into great detail, you cannot just put a "big" cam into your engine, even with replacing the heads, without also upgrading the intake, fuel delivery system, exhaust, torque converter if applicable, and rear gears, as well as a few other things. Is all this in your budget? Is this the kind of car you are looking to build?
Steve
