indeed Tim, had to replace one and forgot which way round they go. according to the micro fiche the appear to go both the same way up into the barrels but when fitted the barrels wont sit flush down with the cases even with some gentle persuasion(!). tried reversing one and it fits but this would mean oil travel would be up from piston 1 side and pressurized down on piston 4 side(which in writing it i seem to have answered it ?
the oil flow up to the camshaft should be pressurized on both sides meaning the valves should be facing both up. perhaps some gentle honing is in order for the new valve