It depends. When I built my 4.1 I used Federal Mogul pistons..
I ended up having to deck .035 off the deck and have Cometic make me some very expensive .027" gaskets just to barely get 9:1. ...along with all the hoops to make the MLS gaskets seal of course. Then I had to shave my intake manifold.. twice (it swelled back up overnight before I installed it).
That's one of the reasons I made my pistons the way I did. I would have just got off the shelf FelPro 1000s, left the .035" of meat on my deck and had a gasket that's easy to seal (and buy).
The bad part is when I tossed the FM hypers and put my slugs in, I was committed to the Cometics since I shaved the intake.
I don't think I answered your question though.