He also said the dome is probably around 1/4" high.
Don't think there is such a thing as a "custom" Sealed Power piston, must be something else? Anything on the underneath side. Looks a little like a KB above the top ring.
Better find out for sure what they are for,, or measure the pin height for yourself so you don't buy them and find they don't work for you. For comparison sake, think you will find KB website shows dome height and volume if I recall. Might be this one with .290 dome height, 27 cc dome. http://www.kb-silvolite.com/icon/ico...tails&P_id=368
That would put you roughly around 10.5-1 with 118 cc combustion chamber on a 4.310 bore