I went thru this problem when we built my one last time ! in the end we had valve clearances cut out ! simply because we had the head skimmed and were using bd10 and bd14 cams ! it was simply a precautionary measure as the last thing we wanted to do was bend valves or damage seats or seals ! forthe sake of £20 per piston its gotta be worth it !
ive had it done on the new one aswell !!