Now which do you have?
1 1/4" Flange , 1 7/16" Bore
or
1 1/2" Flange, 1 11/16" Bore
Flange is the c-to-c longest distance on the throttle base mounting holes.
Bore is the big hole in the bottom of the throttle base.
It's hard for me to recommend which manifolds you should use on the rebuilt head. There is plenty of personal opinions and hot rod articles on what works best for a 292. I've found that intake and exhaust manifolds on an inline 6 can take time (heating & cooling cycles with retorquing) to settle in and not leak so I like to do it once and not mess with it again. Since you already purchased the new manifolds, I would use them.
Your engine break-in needs to be uninterrupted and another reason why I recommend using a known working carburetor. You may be busy fixing leaks, tightening loose bolts, while keeping an eye on water temp and oil pressure.
It's the small base 2G. 1-7/16" Bore. Main Venturi 1-3/32". Small Venturi 1/8". If the jets haven't been swapped out, the book says they are 0.055.
In all my research I couldn't find any reviews on the Aussie Speed intake, but I am in contact with a guy, he is building my adapter plate for the 2G, and he knows people running the Aussie, and said it is a good performer, better than the Offenhauser and Clifford. I'm excited to get this thing finished so I can run it in my C20. Definitely the last thing I want to do is mess up the break-in procedure, so I will be making sure all T's are dotted and all I's are crossed, I purposely transposed those...lol... I'm goofy like that, but detail-oriented.
