There is someone who is doing the Gas ignition conversion on the Supertigre 90 engine. There are some mentions and photos of this version in the Vintage and Antique Forum in the Waco YMF thread. It may be listed on page 1 in the Table of Contents. If it's not listed there, it is in the first half of this very large thread (276 pages). It is there though.

Bill, AMA 4720
WACO Brotherhood #1