I did a KL engine in the late eighties when l was playing with 2 litre car engines. Used, l think, a 1.00 mm o/s 1100 piston for about 280 cc. I made a big inlet valve by cutting down a blank Manley Ford 2 litre item. I reseated it and ported it and made a 4 stroke emulsion tube carby from an IT 250 34 mm Mikuni. Piece de resistance was the cam. We stellite welded and ground the old Repco Brabham /Wade 161A formula 1 profile on the inlet, something else on the exhaust so the valves didn't touch each other, shortened guides, found some springs. Pipe was quite small bore, down, and with a slow taper megaphone. Probably 30 hp at 10000. Went well.