JDM non-turbo dohc engine valves

I have 3000gt that im working on and the car broke the timing belt and the valves got bent in the front head. well when i went to mitsu. to get valves i got the non-turbo valves. it seems that the US spec engine must have longer valves or something because once i tighten the cam down it does not get compression in any of the cyl. im out of ideas and was wondering if any one knew the correct part number for the valves i need or where i can get them. thanks alot