block pics as requested, one of the pistons-
stamped 85.27 and 0.5+
i've roughly measured the bores of the block and there approx 85.5mm-

showing the top of the block and oil filter position
the smallest gap is 6mm between each of the bores-

showing the blocks stamp, cvh-

showing a number on the block positioned behind piston one-


And i measured the standard gasket, its only approx 83mm safechav the metal edge of it gasket is pressed where it averhung