Yes, My rims were originally 3 Bolt. The 7" Rims I get from Strerdy Pouducts are the only 7" rims I know of that will fit the 4 bolt hubs. You can make yourself a pattern to drill your wheels out of a piece of plywood. Cut the outer circle first to fit snug into the wheel. Then with wood in the center of wheel place the 4 bolt hub "studs" down so they are setting on the wood. Center hub in wheel, To make this easier you can wrap a bunch of tape around outside edge of hub to take up the slack. When hub is in center, place a short 2x4 over end of hub and hit 2x4 with hammer hard enough to make impressions of the wheel studs into wood. Drill those out and you have your own pattern. I use 1 of the original holes from the 3 Bolt pattern as one of my new holes for the 4 bolt, It gets oval'ed out.
And yes, Its easier to make Hiem Adjustment with chain off, Because you have to push rear end over enough to rotate the Hiem with the spacers out of the Hiem.