Cover it with lime.
Oh you meant HP?
You will get a little more, probably a LOT more, just by overhauling the engine, period. It's definitely way-way down on power now.
Most of your rebuild kits are overbore kits that will bring you up to, I think, 164 CID. I'm not sure you can even purchase a stock bore kit for an H in this day and age.
You don't need "fire dome" or "fire crater" pistons specifically. Any "stepped head" style piston will do. Like:http://www.yesterdaystractors.com/Farmall-H_Basic-Engine-Overhaul-Kit-Less-Bearings-C152-Gas-Stepped-Head-Pistons_BEKH1156ALCB.html