A7 head with 1 1/16 inlet???

[muskrat]

G'day Alan,
 yep a 400 would be pretty close. I run a 32mm concentric on my '51 A7 ('57SS top end 357 cam and straight through exhaust no air filter) with a 420 mains.
Dutch, the car hit the gutter (dirt road) the trailer jumped it and side swiped the tree. All at 60MPH. The XT didn't budge and was OK.
Cheers

[Seabee]

You may have trouble with turbulence at the intake inlet.  It being smaller than the carb bore creates a "step in the wrong direction."

Joe