Ingersoll, 10cu in, a water pump and a taller rad.

The C and SC were pretty nearly the same. The C had 3 inch pistons and the SC had 3.125 inch, the block though was the same as they were a sleeved engine. When they went super in '48 they added a water pump and a little more capacity in the rad, raising the top tank by I think 1.5 inches, meaning a taller grill and tin from there back.
New engine kits where I've seen them are only availlable in 3.125 pistons so when a C gets rebuilt they get the extra juice.