That video shows a nice running engine Andy-the 09 and 12 MVVS throttles are good-and used to be available from Hobby Club-a quick check confirms they still have the 1.5cc sized one listed for $27.50....and it has an 8mm shank......that means it could be threaded 5/16-32 without any issues-5/16" is 7.94mm-so a normal split die would do the job easily-you wouldn't even need to machine the shank down...
ChrisM
'ffkiwi'