The DGW drum and nipple would not be the route I'd take. After removing your old drum and screwing in the new it would be a crap shoot as to where the nipple would be in relation to the hammer when tightened down. Pics of your situation could help.
There's an adjustment procedure to get the nipple to line up with the hammer.
The stem can be shimmed with a washer, or the inside flat part of the drum can be filed.
It's not difficult as long as the old drum can be removed without busting off the stem.
On the other hand, the over-sized nipple may not be as secure as the nipple would be on the new drum.
And a new nipple is even included with the drum at a fairly low price.