Effective Cleaning Power equals GPM X PSI.
My advice is to have a minimum of 2.5 GPM / 3.0 to 4.0 would be better.
But, with that being said, hopefully there is an manually adjustable pressure valve so you can control the PSI.
Advertising tends to focus on PSI, but increased GPM with lower pressure is what I prefer.
A 5/8 to 3/4 line from the water tank to the pump should ensure that the pump will not starve for water. But, is that going to be gravity fed or pressure fed. I would go bigger input line if only gravity fed.
Maintenance is important. Do not run it hard and hang it up wet.
Flush it out and lube fittings before you put it away.
I have an old Craftsman from 15+ years back that has a Generac engine on it.
It still works, but I have had to replace pump gasket, pressure relief valve, oil sender, and of course the periodic replacement of oil filter, air filter, spark plug. No problems with the engine in 15+ years. You may want to look at installing a glycerin filled pressure gauge which I find helpful in knowing exactly what the washer is "really" putting out.
These gauges usually vibrate themselves to death after a couple of years.