The Dominator sounds good to me. I think the KK needle is machined out of 3/16" sq.brass completely and the tubing soldered onto that. I have a pic of a snorkel I made as a kid for the TD .049 to use a remote. It had a tight fitting cowl and made removing the top easier without losing the needle setting on a 1/2A control line speed plane. I think I made a big venturi for it too, but it is gone over the years. It is just 1/4 - 32 thread on the .049. I would imagine the .020 could be drilled out to just a bit smaller than the collector ring size if you want to go faster. A collector ring groove could be machined on the inside of the needle valve assembly so the hole could be drilled even bigger if a new venturi is made. You would then only be limited to the minor dia. size of the thread. We used to go to .125" on the .049, but I have noticed the Fora is a full .250", so they must have found it possible to go huge. I don't have an .020 to measure or play with for comparison unfortunately.