Reliable Motor Cycle Repair/customization In Bangkok

I'm looking to buy a rather used old 650cc honda motorcycle that needs some electrical and cosmetic work. As I expect this to be my daily ride, I'd really like to build a relationship with a good mechanic who really understands old Hondas and can import parts for Japan as needed. Also the bike has some rust spots (only cosmetic) and could use a new paint job so a place that has some custom experience would be my dream.

So far, asking around, it seems that the shops are either some kind of exclusive clubs (which are typically for a specific brand of bike, not sure how to join, and seem to cater to 400k+ baht bikes) or places that maintain scooters to keep them running. I guess this reflects the fact that there doesn't seem to be a middle range braket in Thailand due to the tax rules but I would expect there'd be some place in Bangkok that is the exception to the rule.

Appreciate any recommendations (or avoidances) from anyone experienced in this matter. FWIW I do not speak Thai but I have staff and a wike who do so they could translate if English isn't an option.

Many thanx!