Tim - I don't know if they will warp on the shelf or not. I would suggest assembling, but applying NO torque to the top screws. Also, if your memory resembles mine, an attached cardboard tag suggesting screw tightening before use. :rolleyes:
On the carbs you use, figure about 3 years before you have warpage problems again.
And you might consider the ABC's of carburetion for future projects:
(A)lways (B)uy (C)arter
Jon.