Comp check 340
If you just have the type of gauge that you hold in the cylinder by hand (doesn't screw in) that's your problem. You need to get one that has a hose. I have a K-D that works fine getting around the headers. For more room I've found that you don't really need the little extension on it either.
BTW: for pulling the plugs I've found wobble extensions works great. Much better than universal joint types.