Pistons specs question for 340 build

When buying pistons......

1970 CHEVROLET C10 PICKUP Speed Pro L-2256F 30 Speed-Pro Forged Pistons | Summit Racing

That's a flat top with valve reliefs. POSITIVE 6.1 CCs. Right on the ad.

Here's the dome.

CHEVROLET Speed Pro L-2252YF 30 Speed-Pro Forged Pistons | Summit Racing

NEGATIVE 11CCs right in the ad.

So BE CAREFUL is my only point.