First time swapping edelbrock aluminum for 915 cast iron heads.

What's gonna happen to your cylinder pressure?
Aluminum needs more pressure to break even.
Then they like 175 to be aggressive. Then they like 185psi to wake up
Some guys are over 200 on pumpgas,they say, IDK,I haven't tried it yet..
I run 185 on 87E10

Not if they outflow the iron heads. I went from 906's to eddy heads that were blueprinted and mildly ported. 88cc chambers on both.