I bought a Teague extended for my 612. Arrived today. It didn't fit. It was 0.02mm too large on the thread size. So 3 turns in and it bound up. Used a 1mm pitch thread file to make it fit.
I did speak to the people at Teague. Who were happy for me to send it back for them to sort but I didn't want the faff with the postage.
Teague will make sure your choke is correct if you send one of yours as a pattern. Just call them first to arrange.