It's the "African" model made to look like their larger "safari" rifle. It's a special make up for Lipsey's. Lipsey's is well known for commissioning relatively small lots of "non-cataloged" models and chamberings from Ruger in just about every model Ruger ever made.
I suspect the front sight is soldered in place. The bbl is 22" long, so, you could just cut it back to 20" but you'd ruin what's almost certain to be a collectable piece.
I didn't realize it when I linked the Gunbroker ad. That rifle is at Dry Dock in Carrington, ND. A guy could just drive over there and nab it without paying shipping. They've got a nice store, never know what else a guy might walk out with, certainly worth the drive to save shipping and take a peek at the rest of the store.