Thank you all for your replies. Pilot DAR, I get your point and it's almost the same with mine in regards to the H2AD engine after all I've been reading about it. I've flown a H2AD Cessna for about 12 hours, but that's almost zero to have any relevant opinion on the engine also considering my overall limited experience in flying, having my PPL only for two years
In regards to the possibility to get an extension, from what I hear CAA will soon release the first extension for a newer Cessna 172 so having a precedence will probably help me getting mine. I'll call them on monday and ask details, rumors is all I have for the moment
I'll also have to look into the STC details for the MOGAS as you suggested. There are some major gasoline retailers in the area as OMV, Agip, MOL that have decent auto fuel, but I don't have any other details on the quality of the fuel. I know OMV's 100 gasoline is imported from Austria and not produced locally, same goes with MOL's 100 that is imported from Hungary. The regular gas is produced here by Petrom (OMV owned now) and sold by all others.
Dan, I am aware that the costs of a major overhaul or major maintenance costs versus a paint job. Probably a paint job here will not be more than 2-3k even less, depending on the shop. And you're right, they're priced around 30k euros, so pretty close to your estimated 25k pounds. Unfortunately is all the budget I have for the moment ... so I have two options, either to spend this money now on a pretty used Cessna, or wait a few more years and to hope I'll have a more relaxed budget in the future for a better airframe and engine and rent meanwhile ... hard decision