The feature these EQ heads have that is unique and incredibly desirable is their LA manifold bolt configuration. I asked the machine shop owner in my town if he had ever drilled Magnum heads to accept LA intake manifolds and he said no. I didnt ask if he was willing to because I already had the EQ heads with the desired intake pattern. I had this shop check the guide fitment and seat sealing. He said it was all good out of the box and the quality of springs retainers and valves were good quality as well. I had him cut down the guides for increased lift cam compatibility and then began porting my heads. I was certain I exercised due diligence. But Ill mock them on a block eventually.