4seventy,
I don't think it was any worse than doing a side by side but the surprising part for me, was how much trouble I had getting it regulated. It started out great when shooting it with temporary spacers and clamps, but when I started working with it after soldering it up, it started getting stubborn. I wound up shooting almost 200 loads through it before I got it regged and sighted in! In theory, it should be easier to regulate an over & under, but this one proved that not to be true. The next one might just fall in line and be easy, you never know.
The main thing that was different was the spring loaded ejectors, you need to be very careful with them, both during dis-assembly and when building them up for the 45-70 rims. They have stiff springs behind them ! They must be removed before clamping the monoblock in the vise to work on it.
If a person wasn't careful, he could end up shooting an ejector clear across the room, and in my shop, that would never do!
The gun is regulated for 300 H.P. bullets with a moderate dose of IMR 4198 for about 1500 FPS or so. Not a heavy loading by any means, but it will shoot clear through hogs and black bears, and I think that is more than enough for most North American game. Looking back, it could have stood heavier loads, but at the time, because I knew Ruger used cast parts in it, we decided to hold the loads down, somewhat. I now feel the frame is up to about any 45-70 loadings except the Ruger Number One loads. As I said, I don't see any reason to stress the action more than necessary.
Would I do another one? Yes, but not in any hotrod calibers. The 45-70 is just about perfect for this conversion.