I'm not that interested in this thread, but I seem to recall some articles published by the load testing guy addressing exactly the long shell in a short chamber pressure question.

Drew- OP said NID in good condition.

With regards Ithaca Flues models and higher pressure shells, dumb idea. Not that the barrels will blow, but that you'll break the corners off the top of the stock.
I have 6 here right now with broken top corners. It's a design issue. No way to draw the stock into the action. When the wood shrinks a little, it gets pounded to pieces. Well, actually fractured off.
So, while they may not blow, the bolting gets all sticky, and the stocks break. YMMV.

Out there doing it best I can.