Do you have pictures of the pistons? Do you know the part number of the pistons? Did this well known builder tell you how far down below the deck the pistons are sitting?
Even if the pistons are lower compression KB pistons, why wouldn’t he simply suggest a piston upgrade without new rods?
Your 68 CC chamber Speedmaster heads; are those the CNC ported version?
@Bobzilla They are KB107's. Flat top hypereutectic. Alan said they are .100" below deck. Speedmasters are Speedmaster PCE281.2149 CNC-Machined, Assembled, Aluminum, 68cc Chamber, 190cc Intake Runner, for Hydraulic Flat-tappet Camshaft
