The way I see it is your butt dyno will never tell the difference between the two heads. If doesn't go to the track you'll never know the power difference. Do what you can afford.
I agree with this. I think the OP mentioned that his car is just a "street' car, so if it were me, I would just keep the 915 heads, and do a little work on them to work with the cam and intake. No reason to go overboard for a street car, a street/strip car that goes to the track often, or a full bracket car would be a different story obviously.
