At a large power plant, our feed pumps and booster pumps, and condensate pumps are api610 or meet the spirit of api610 :). Also other pumps that see elevated temps or considered "critical" are api610. Pumps that just move low-temp water around tend to be ANSI b73,1. If you have a specific...
As mjcronin already posted, Talk to one of the major manufacturers that have seismically-qualified nuclear safety-related pump designs. That would be flowserve, Sulzer, goulds, Hayward Tyler in the US. You're probably looking at seismic supports/rings near the bottom of the can.
That may be an ANSI (b73.1) end-suction pump - or at least the bearing housing. Just search for b73.1 and you should be able to tell if it is built to ANSI dimensions.
Assuming you're not a rice farmer and that "flood" means an avg depth of 6" to make sure water gets everywhere...requires 4 acre feet in eight hours, or 2700 GPM. That's 100 HP imparted to the water, requiring about 150HP at shaft, 130 kVA in the line. Evaporation should be negligible compared...
You thought about a vertical installation? Not sure what's going on in there or how fast it is turning but I imagine you will need some radial bearings and a thrust bearing. maybe easier to suspend the rotor and have some low-load guide bearings.
Typically they are not designed for differential pressure of more than a few inches water. They are normally held in place with o ring and very light press fit. Me thinks you may need a mechanical seal.
Or maybe a low pressure chamber with a throttle bushing to break down the pressure...
For materials, see link below. For pumps of this size, You're probably looking at 316SS for stationary castings and super duplex or equiv for internals. Catholic protection will be considered.
Vendors: All of the big names should have plenty of experience in this.
Techniques to detect...
Surely the client is talking about corrosion of the flange, not the fasteners. Assuming normal outdoor installation, your setup sounds fine to me and fairly typical.
