Honda water pump to generator?

Most of my spare time in janaury has gone in helping a family have a proper tidy up around their property. (Those who are waiting for willow swaps it'll be posted soon...)

For my labours said family member is giving me a half framed 4hp honda water pump, no hoses. It ran fine in summer. I could just about make use of it to pump water from the butts on plot 1 upto plot 4 - about 30 yards. But to be honest it'll be a a chore and I might as well just use a watering can as usual. I have more use for a generator.

My question for the tecnically minded is: Can i take the pump off and fit the appropriate alternator to turn it into a generator? New honda engined generators seem to be priced from £300.
Its a honda 4 stroke 4hp engine, I believe a GX120 with a horizontal shaft. If it can be converted does anyone know what type of generating alternator - preferably AC 240v- I need, where could i get one from and how easy is it to convert? I think a 4hp engine will comfortably run a 1.5 - 2kw alternator.

I suppose I could flog the engine/pump on an auction site and then buy a complete 2nd hand generator, it just seems a shame to swap a good honda engine for one I know nothing about.

any advice gratefully recieved.
thanks amc

Thought that may be the case gwiz, prob at the minute is that i can only afford a new cheapo 2 stroke generator, those you see advertised in the sunday papers at 90 quid... don't look v. good quality mind. I'll prob be best to keep an eye for a good second hand 4 stroke genny... or even better a small in generating  size (but not weight!) single cylinder lister diesel like this:
http://www.boatsandoutboards.co.uk/view/F199342 

Thanks for the advice, amc