Can u fit a 16v engine to my Rivage in Lincoln/Newark area?

hello everyone. Unfortunately I don't have much technical knowledge of the mk 1 but bought a 118k mile rivage with a bit of a jerky engine. Paid a good price for it and planned to get the problem sorted by my vw mechanic. After taking her in for an mot (of which she only failed on low tread on a tyre) my mechanic friend said that I could spend more money trying to source the problem of the jerky engine than what the car is actually worth.

The main problem is the revs sit at idle over 1k revs and 1st and 2nd are always jerky. Third/fourth and fifth go well but I am sure she isn't as fast as she should be. Confusingly I have taken her over 100mph and she kind of liked it.

Looking back over the paperwork she has been serviced regularly but she had the fuel filler neck replaced and all the fuel injectors were replaced just before I bought so I think i bought it as the previous owner realised that it wasn't just a quick/cheap fix. I have checked the HT leads and they also look pretty new so apart from that I ma a bit stuck. I bought this car so I could have a nice summer drive and have loved driving the car but really want the engine to run sweet. i used to own a 1.8 clipper and the engine was faster in that than in this gti so I know she's not running well.

So my thoughts are to have the engine replaced and hopefully this will resolve the matter. I have no idea about the technicality but understand that fitting a 1.8 16v from the mark 2 is the easiest swap. I will get 130+bhp - although I do understand that my model was fitted with a catalytic convertor so I will loose 25 bhp but that's fine. After having around 110bhp in such a small car is bound to be better than what I am currently getting anyway.

So the big question are:

a) Will it be a simple job fix by paying a mechanic to fit a new engine?
b) if so which engine do I fit that will give me good performance and less hassle (ie: lower costs for me) for the mechanic?
c) Is it ok to buy an engine on ebay etc for around £50-200?
d) Does anyone know any good mechanics in the London or Lincoln/Nottingham/Newark area that could do the fitting for me?
e) Or is there anyone that knows a good mechanic that could supply and fit a good recon engine for me for a good price.

In addition to this I really want to take the car off the road for the next 6 months (starting at the end of this month) so i am very happy to leave the car with someone for them to work on over the forthcoming months.

If anyone can help with any of this it'd be much appreciated. I love my cab and don't want to start regretting buying it as it looks great but this engine issue is very frustrating.

thanks very much,

Jon

(J450NJO)