Match drilling is the same as reaming out the holes. Each pre-punched hole is undersized and when you align the skin on ribs etc. you match drill making sure both the hole is true and even between both pieces. This takes away stresses in the airframe and makes sure each hole is as perfect as possible.
I was able to match drill the right tank Z brackets and skins just like I did on the left tank. Pics are below. This tank didn't seem to line up on the spar as easily so am worried about how it will turn out down the road. Basically in airplane building you end up doing so much work, then when its all done and riveted it better line up. If after I get this tank done the Z brackets don't line up for bolting on.. then I am in trouble.. It has happened to other builders so I am nervous and trying to be careful here.