I have had both the new small cap and the original larger cap installed. The larger cap was definitely a pain to deal with. Had to pull distributor to get valve cover off. The small cap I did have to clearance the valve cover lip, most of the edge lip that is vertical to valve cover gasket. I am running Edelbrock aluminum heads. I had previously made clearance for a Mopar style electronic distributor so I can’t attest to the head. If I get to the shop tomorrow I will get you some close up pics of the area. As far as the distributor itself I absolutely like it. Been no issues. My car is primarily street and the MSD setup would get hot due to not getting out of the multi spark rpm and go stupid on me.