Because it is a standard and readiliy available pump virtually and diesel fuel injector place can rebuild and set them for you. It does require proper instruments to set the pressures so if you dont have a pop off tester then take it to a specialist.
As another option being on the rivers over there you must know of some boat repair shops on the river, they too can help.

We have a product here that looks the same but is made of stainless steel and is called a scourer. Mainlu used in washing up. They look like a neat ball from new but then flatten out and eventually will look like yours. I have heard of timber floor treatment being done that way but never seen it.

Take a visit to Pearns World, there is a heap of toys to choose from, just not for sale.

Try not to be hard on yourself. We have all made mistakes and by doing so we learn by them. In time we hope to see some more progress as it happens. Stay calm and continue with the great work you are doing.

Nice little and very reliable engine. As for value it is an age old question which for me comes down to supply and demand. Have a look at the usual auction sites in your Country to see how many are for sale and how long they have been listed and what they sell for as well.
I cant put a price on it at all as I have not looked for one but sometimes when I have an item I want gone if I get my money back for it then good, if not how much am I prepared to loose on it if anything and hold onto it until the price rises. The good thing for you is that you have confirmed that it starts and runs so that is a huge benefit to buyers. As a suggestion do a YouTube clip of a start up and run which will confirm what you say in your advertisement. It presents well so anyone with a footpath roller, boat and then marinise it, or depending on what RPM it is governed at a good standby engine for a genset.
Wish you well selling it.

if your injector is the same style as in reply 23 then pressing it out from that side appears to be the way to go. Keep soaking and a small amount of pressure and maybe introduce some heat. Even heating and spraying with WD40 to get it to draw in deep and quicker. If still no joy then more heat is how I would aproach it

Well done on the recovery og this special little engine. You may be surprised at how little it will need to run again. As stated, what it looks like on the outside may be bad but inside still good. Thanks for the pictures.

If injectors and pumps are good and you have confirmed that they atomise the fuel by hooking them up while outside of the engine and cranking it over then maybe a valve. I suggest you check they are atomising because there may be a problem/blockage in the fuel lines.
I just had a thought. Is this a 3 cylinder engine as it is listed as a HR3? If so have all injectyors and pumps been serviced?