hello and welcome
there are lots of Gilera son your side of the water.
You have uncle Bob as source for Gilera parts
http://www.bobwrightmotorcycles.co.uk/
More than we have here around
Beside this you had Pete Fishers GeN
Unfortunatelly he gave up the mailing list and the website
Looks like internet forums are way to oldschool and will die
Everyone ist now using the so called social media
If you need data or your Gilera the registro storico in Arcore is a good source
https://www.registrostoricogilera.org/
You will also find some workshop manuals in the net
Good luck and happy wrenching
ciao Joachim