Hi Dane, To use a 26 MM on the Ambassador would require more changes than you would want to make. I purchased all the 26 MM carburetors from Whizzer several years ago, and sold all of them but the last 3. The last 3 are for my personal use only and not for sale. In order for the 26 MM to work correctly on the motor you would need to increase the intake port I.D. to at least 55/64", and would also require the intake manifold to match.
Have fun,