Hi
Looks like a PP with a larger fin grafted on . Most spares are not a problem on these ,apart from the castings. Normally the only parts that wear are bearings and seals The rear bearing should be a D U bush made by glacier bearings This should be lubricated with EP90 oil ,note the orientation of the seal The front bearing is an automotive bearing ,there are two kinds just take it to your local bearing stockist to match he will have the DU bush as well The seals are all common automotive seals again from yor bearing stockist but do note which way they are mounted when you remove them and replace the mild steel springs in the new ones with stainless,these are easily obtainable now that they are specced for the catering trade. The collett that locks the impeller to the shaft will break in time or if it is overtightened, an original was £200 or so when I last looked, but any competent machine shop can make one very easily They are made from polyacetal rod ,this can be sourced as an offcut normally or even on e-bay. do not use nylon,it looks similar but is not suitable as it absorbs water and expands
The performance of this boat is hard to judge ,it would definately benefit from a larger jet but try it first without throwing too much money at it the problem will be that jets this small are very sensative to weight and your engine and hull are at the top end of this jets capabilities