That was on Flee bay about 4 years ago, it was on my wish list if I won the lottery.
Hears a link to a chap that quite often has Gnome engines for sale, usually 3-5k. That a hell of a lot of power for the money.
http://www.everettaero.com/
Then go to engines and then Rolls Royce Gnome
The Gnome engines are up to around 1250 shaft horse power and around 142Kg inc gearbox. Fuel wise they are a relatively high compression so not too juicy. Would happily run on heating oil so half the price of marine diesel.
Recon you could buy that boat, get it up and running for around 15k inc engine and box