my zvh 2.1 convertion is about to begin. ive got a1.9 zvh in at the moment with cossie managment but the bores want de glazing and new rings etc so all the parts will fit convertion apart from pistons and rods so do i need 86.50 mm bores for 2.1 piston and whats the best way to lower compression to 7.51 or whatever and would you wire ring the bores