Before bumping up horsepower even further in our '97 F-350, I decided to formulate a backup plan...
I recently came across a good, rebuildable core 7.3L Power Stroke for just $250. It's an early '99 model year engine, so I know it has forged connecting rods. For now, the engine will remain in storage. But, with the "push the limit" gremlins baiting me to pursue 550-to-600-rwhp on the current '97 engine's stock bottom end, it may one day be needed. As it stands right now, if the time comes (where a rod leaves the block, or something else catastrophic occurs), the spare engine will be torn down and rebuilt back to stock (and the go-fast parts swapped over: valvesprings, pushrods, head studs, HPOP, turbo, injectors, fuel system) and de-tuned a bit to live.
OR, Plan B could mean a slow, progressive buildup of the '99 engine, starting right now. Billet rods, aftermarket pistons, cam... could all be on the table in this scenario. We'll see how things go if we end up experiencing a stock bottom end failure firsthand, and decide from there.