Hypertec make a dished (12cc?) piston to suit 351 crank & 351 rod with closed chamber heads($438.61), or can open up the chamber a bit with burr & use flat top piston,
https://www.precisionintl.com/StockSearch.aspx?Search=PFO351C81H
Hypertec also make shorter piston suit 351 crank & 302C rod, flat top $438.61
https://www.precisionintl.com/StockSearch.aspx?Search=PFO351C683H
zero decked 351 with flat top & closed chamber heads are easy 11.3:1 or standard deck around 10.3:1, zero deck 351 with dished 10.1:1
also known for the locks to pull through standard retainers over 5500, best to upgrade valve springs, retainers & locks, & is needed for larger then 0.500" lift cam