Thanks for the info all. I was asking because I'm trying to decide whether or not to install my 360 with the stock heads and change them to better flowing heads later or to blow off this year and just keep the engine out and put the heads on for next year.
I wouldn't suggest skipping this year if you are ready to install what you have. Once you put it off, it becomes easy to put it off again, and again. Next thing you know, a few years have gone by and your car is still sitting with no engine.
As for swapping heads in the car, I will never do that again on a A-body with hedders. It's actually easier if you just take the engine out again. Engines come out so easy, it actually takes me less time than fighting everything in that tiny engine compartment.
Either way, good luck with the project.