You could use a model 28-3 or 27-3 or later cylinder that was not recessed or you could use an earlier recessed N frame cylinder and either machine the rear of the cylinder to remove the recesses. The ejector star would not need to be machined. This would allow you to leave the frame lug stock. There are usually some on Ebay for under $100. I think I might have one in my parts pile that I would let of and machine the ledge in for you.