Source for a tap

[GatzkeCues]

bastard tap

I believe this could be what you are after.
It appears to fit your description of yet another bastard thread tap.
This was robbed from one of those Chinese import Fierce Eagle cues.
The 2 on the left.

 

[DRPoolshooter]

Make your own tap

...if you happen to have a SS pin of the same thread lying around.

http://www.cnczone.com/forums/diy-cnc_router_table_machines/148118-tap_making.html

 

[GatzkeCues]

tap

That is similar to what I did. I ground 3 grooves into the far left one.
If you want, I could either make an insert, lend you the tap or possibly make another one for you.
Just say the word.