Here's the deal with "can it handle that much HP". The answer is... Most likely!
What I've learned is that you have a small chance of blowing a head gasket, no matter what you do. Even N/A!
If it's a gasket that hasn't been changed since the motor was built in the 80s... it's going to go sooner or later.
In my case, I pushed 250 (wheel) HP(320 crank) out of a stock 88 7.3 motor for a full year, with a sketchy gasket - see, I had the belt tensioner break, the engine got hot as I limped it to an auto parts store, and when I got back home I saw coolant trails out of the head gaskets on both sides. I decided "well, if it's going to fail anyway, why not have fun?" and put my big IP on it, cranked up to max!
A full year plus later(this included many towing trips and daily driving, probably 10K miles total), with intermittant weeping of coolant from the gaskets, it finally failed into the water jacket. Still ran on all 8 cylinders, but produced lots of bubbling in the overflow and lots of coolant out the exhaust.
I'd say that isn't stressing it a lot, considering when I first saw symptoms and when it actually failed.
My other truck (currently) has a Banks kit on it and maxed pump, and it's literally maxing out the 15 psi gauge whenever you get on it. my friend has been DDing it for a few months and, well, no issues yet. We've pulled some pretty big loads with that, including a large IDI Van about 500 miles(at 60+ MPH)(Note: this truck had a rebuilt motor in it at some time in the past, so I know the gaskets aren't as old as the truck).
Head studs will definitely add some added safety factor, but I'm fairly convinced that a stock-type turbo just isn't going to push enough pressure to blow gaskets at this point, and one of the main advantages of adding headstuds is you do gaskets at the same time.
I don't want to be too negative or positive here; I've had good luck with my setups overall, but it's just something to be aware of. Head gaskets blow on cars all the time - they seem to blow less on IDIs, but remember the age of the engine.
Another advantage of turboing and making sure your fuel is matched with your air is EGTs. Keep the temps reasonable and the engine will last a lot longer. Heat is what stresses gaskets and everything else, and a N/A motor can actually produce higher EGTs(due to the lack of air at higher RPMs) than a turbocharged IDI making double the power... simply because you have more than enough air going in there.
edit:
Just to point out, a RD2-90 isn't a 'special' pump. it's a cranked-up stock-spec pump, which is why the cost is low. Mel and Russ can both come up with similar pumps, and they should all work well enough.