jet conversion

[sambo]

i am looking at building a new boat which i would like to be jet powered.
my idea is to buy a 4m ski boat and put in a 3 cylinder 1200cc jet ski motor in it
(120-140hp) i would like to be able to use the same jet unit fromthat motor but am unsure if it will work, i have sum people saying it will work and alot saying it wont. i like the idea of using at jet ski engine as they are light and reasonably cheap and easy to get a hold of. a lot of people say that the jet drive is to small for the size of boat. if this this is the case is it possible to marry a diferant size impeller and jet to jet ski motor. any info on this would be great!!!!

some pics of the boat im looking to use can be found at
http://www.viperhps.com/