nah, it is simple
seems to me, there are two ways to make this turn the right way
the easiest way (providing the intake and outlet are the same sizes) would be to pull the impeller of, spin it around and re install it.
Looking at pix, turning the impeller prob wouldn't work, but Treblig's on the right track, see if a reverse rotation marine pump is avail. It'll be costly but may have the best result.
I've had experience with the wrong direction pump on a marine engine, everything seems fine till about 2000 rpm-ish. Owner put a standard auto pump on a reverse engine, cuz the car pump was <$30, and the correct marine pump was $130. Same auto casting, distributed by Mercruiser, with the impellor vanes straight, 90* to the shaft, and sold it for both direction rotation, they just plugged off the heater hose port with a frost plug.