what I do to keep the O rings in is use a can of spray adhesive you can get it at any auto parts store as long as the domes are for the same bore size not big bore domes I would use them just clean the surfaces of the dome and oring spray the oring let it sit 5-10 minutes and stick it in works great also I have used both domes in that head and they are the same if the hemi head isnt cut for the pro domes grind off one of the holding tabs