I am not a 2gc expert by any means. This is what I know. Depending on which mono jet came on your 292 it would be either 250 or 210 cfm according to Doug Roe's book. There is supposed to be 2 sizes of the small base 2gc that has the same size hole as your stock air cleaner. One has1 3/32 Venturi and 278 cfm. One has1 7/32 venturi and is 320 cfm. I have never seen the 7/32 version, but that doesn't mean they exist. Both carbs have a 1 and 7/16 throttle blades.
There are 5 sizes of the Large Base 2gc carb. One has 1-3/32 Venturi and 1-7/16 throttle blades just like the small base carb. I didn't know such a carb existed til I measured one of the carbs in the garage.
The other 4 large base carbs have 1 11/16 throttle blades.
The Venturi sizes are 1-3/16, 1-1/4, 1-5/16 and 1-3/8.
If I were trying to run the stock air cleaner I'd go with a small base, the bigger Venturi if I could find it. This assumes that you have the stock cam. I DO NOT know if the linkage ect will clear your air cleaner might want to try a test fit before purchase. Some early small base carbs have a high mounted choke coil might not clear the carb.
If I were going with a Large Base carb on a stock 292 I'd go with a 1-1/4 or maybe a 1-5/16 Venturi model knowing that the stock air cleaner won't fit. The bigger the Venturi the more sluggish the low end will be with some improvement in top end. I hope that others that know more than me will chime in. Jay
