In my experience doing conversions the 16ga is best suited for 9.3, .375, 450-400, and .45-xx.

.450ne is best suited on a 12ga frame. I'm a jp sauer now, it's finished weight is 10.5lbs w/1lb of weight in the stock and 26" barrels. It balances 1/2" in front of the hinge.

The 450-400 I did was on a jp Sauer 16ga. It's finished weight was 8.75lbs with no weight added in the stock. It balances a little further forward. With 1/2lb of weight added in the stock it would have weighed 9.25 lbs and balanced on the hinge.