The intake port of the TCCD has about as much surface area as a 16mm carb, so any bigger than a 16mm delorio would be a waste unless you port the cylinder.
My bet is that you are just rich. With a Proma GP and and 14mm drilled out bing, and the stock air box (without the snorkel) I was running a low 50s jet. Pretty sure 54 was what we ended up with. And when it was rich it wouldn't idle, especially after it warmed up.
Also don't just time it to stock timing, advance it like almost all the way. If you have a meter and a timing tool set it to like 2mm before TDC. If you don't have the tools to measure it just advance it almost all the way. Timing is a huge deal with these kits, Me and GabeB turned his bike from a non-idling 30 mph turd to a decent ride in about 15 minutes by advancing the timing.
Then tighten up your clutch to compensate for the low end and you should be rocking.
Of course all of this comes after you have fixed any air leaks.