340X heads
Yep I would sell the Xs too, get the magnums you will be happier, better pedal feel on the street at low end. You compression will be good and you can get good money for the Xs, invest it in a cheaper set of heads and i think as Adam said that is a good way to go.
Yep the Xs will work too, but i think you will be ahead and happy with the smaller heads for a budget street car?
But it it is high power big bucks then stay on course and mill like about
.040 - .050 or so to get the compression back into the corrrect range.