I was unable to find that brass shoulder bushing at NAPA or LAPS or hardware store, so I searched online and came up with this:
shoulder bushing I will need to reduce the oal, but if that's all I need to do to make it work, I'm happy. I ordered 5 of them, just in case.
Follow up: The bushings didn't work out. Too much play in it. So, I just fabricated one from a brass reducer, which I should have done it the first place. Works just fine.