I have a good friend that bought a set from Tony and I helped him fit them up.
Here's my take on it:
The barrels are very high quality and from what I've been told are made in Germany, but they are different than the original 16ga repro. barrels made by Kreighoff.
The forearm will fit but you need to be carefull not to alter it due to the fact that it still needs to fit your 20ga barrels.
After going thru this fitting process, if it were me "I'd pony-up the money and have Galazans do the fitting"!!
I think that if you really want a nice 16/20 combo this is a good way to go. I have an original repro. 16/20 combo that is one of my favorite guns. The 16ga barrels on the O-frame makes for a great field combination. I'm gald I bought my gun years ago simply for the fact that, they made so few of them that when you find them now they are expensive.
Buying the barrels and having them fit is a fairly reasonable why to get into a combo repro. Especially if you already own the 20ga.
Here's a word of caution: These barrels will fit and function just fine, but dont expect them to fit absoulutely perfect!