What compression are you running?

[stock50LX]

The pistons I purchased are going to give me 9.7 with my current iron heads. I am now second guessing my decision and wondering if I should and could have gone higher? I want to be able to drive the thing on pump gas. I have no plans for any type of power adder. The engine is a 351 soon to be a 357.

 

[408stroker5.0]

You can get away with anything lower than 11:1 on pump (supreme)gas. Just don't lug the engine.

 

[bhuff30]

You can get away with anything lower than 11:1 on pump gas. Just don't lug the engine.

Probably with an aluminum head and premium you could, but not on an iron headed with 87 octane.
9.7:1 is plenty low to continue using 87. I might go up to 10.3-10.5:1 for pump gas, but I would be listening carefully for detonation and hoping I didn't have to retard the timing a bunch.
A tiny bit of extra compression isn't going to give you that much of a noticible gain in the real world. Error on the side of caution.
Can you mill the head much on a 5.0? If so, you could mill it down a little instead of getting different pistons.

 

[408stroker5.0]

Notice I put Supreme Gas not Regular Gas which is 87 Octane. You could not run 11:1 on 87 octane.
Supreme which is 91 Octane is usually enough but a little octane boost would be a good idea.

 

[5.0 HOtrain]

I run 11.25:1 with aluminum heads and super. Have yet to drive it on the street, but ran fine on the dyno, first test drive hopefully this weekend
mike.