I'm noticing a few forum members restoring old Hondas and such.
As much as I use aliexpress and some use amazon.
and most of my local ebay searches are only national/china...
perhaps ebay in Thailand has what you're looking for in regards to parts and upgrades....
I thought I'd share this particular youtube channel tour of the ebay store...
https://www.ebay.com/str/ottoclassicbike
https://www.ebay.com/str/bkkclassicbike
I personally have not purchased anything myself but I did check out the store and is seems very well priced for what is on offer...