You dont use different pistons and not moddify the the head or run standard domes.
The pistons they are talking about are Wiseco 795 series. They are made for a Long rod crank. You have to run these pistons with BOTH a stock stroke long rod crank or a 4 mill long rod stroker crank. It is because the conecting rod on a long rod crank is 5mm longer. So you need a piston that has the wrist pin moved up 5mm farther other wise the pistons would pop out of the cylinder and hit the head.
A regular rod 4 mill stroker wont require 795 pistons. All you would need to do is have the head machined, run stroker domes, or a 2mm spacer plate under the cylinders. Your adding 4mm stroke to the engine. So the piston is going to fall 2mm farther down in to the cylinder and it is going to pop up out of the cylinder 2 mm.
A Long Rod 4 mill storker will require both 795 series pistons and a cut head, stroker domes or a spacer plate.