Probably the best way to go is to contact Lifan Thailand, they can provide the necessary parts and instructions how to change it. It's probably best, if your Lifan dealer is capable of doing it, otherwise I would recommend Lifan HQ for the conversion.

The engine needs to be opened and parts need to be replaced, this can break Lifan's warranty if done incorrectly or by somebody not qualified to do so....

Thailand and email communication is not the same as in Western countries. We get lots of email from Thai companies and they often call to ask for conformation if I received the email... They did that in the past also with faxes, you received a fax and a few minutes later a person would call to ask if we received the fax... Seems so inefficient, but that is how things work here, so who M'I to complain....

So maybe call them and ask for a personal email address and start the relation like that... sending an email to a person called admin@lifanthailand.com (who maybe only admins the website and maybe not even works for Lifan). Is maybe not the best start.....

"I once wanted to make a set of parts and instructions to change the shift pattern of the Thai Lifan LF200GY-5a"

Did you succeed?
Do you know parts numbers?

I've not heard good things about Lifan mechanics.
If I could obtain the parts, my mech could do it.

Thank you for reiterating that.
Today my mechanic, the manager of Jeleonyot Motorcycle parts,
likely the biggest seller of OEM moto parts in Pattaya,
told me that Lifan could sell him an engine with the desired shift pattern
but not the parts to convert.

If anyone actually knows the contact number of someone @ Lifan who can help,
please advise.