All the 3200 spring will do is allow the engine to spin about 500rpm faster before it defuels. So I doubt your engine will be in danger from higher rpms. Now higher boost is a different matter, I wouldn't trust the head gasket to stay intact with higher boost.
You should seriously consider replacing that head gasket soon….and while the head is off, check the cylinder bores and look to see if theres any cross hatch left, and tab that KDP. You may discover that the crosshatch is still there, even with this many miles and the engine would still has plenty of life left in it. It's not too uncommon for these things to hit 500K (so long as it's well maintained)
I don't know why you would have advanced the timing and turn up the fuel, only to set the waste gate at 17PSI. If you wanted more power, you got the fuel, and it's being injected earlier, but at 17PSI theres not a lot of air to burn it. I wouldn't be surprised if it smokes like a freight train and pulls a little weak off the line
If that IP is weak, you should have it rebuilt or the truck will strand you somewhere. Same goes with injectors. You now have the perfect opportunity to make a few improvements. The 3200GSK is a good mod, but instead of advancing the timing (Pump to the head) put the IP back in the original timing position and pick up a dynamic timing advance from M&H. This will allow your engine to pull hard at low rpm, and pull strong in the higher rpms and will complement that new 3200rpm gov spring. While you're in the pump, at least turn the fuel pin about 90 degrees or get yourself an aftermarket fuel pin. Get some injectors for that thing. Some people will suggest PODs or Marine injectors. Do some shopping here and make some calls. For reference, I went with 5X.012s Thats about the next size up from the stock 1st gen non-IC 9mm injectors (and approx equal to a POD on a 1st gen 7mm injector)
You have one of the better turbos for the 1st gens. Fix that head gasket leak and set that boost higher. Start at 30PSI and go up if you need to. With those mods, that engine should wake up and it won't kill it or reduce it's lifespan
Ed