Ditto to Jon's advice. The most common mistake people make when going to multiple carbs is putting too much venturi area into play. If you want to use the Stromberg-type 2-barrels, you'll need to find some carbs with very small venturis, possibly the ones designed for the old 60-HP Ford V-8. That engine had 136 cubic inches, so two carbs would flow enough volume for 272. Carbs for either the 221 cubic inch 85HP or the 239 cubic inch 100HP would be way too big. If you do some other modifications, such as increased compression, increased duration and lift on the cam, plus some porting and polishing on the head, you can make effective use of the increased airflow capability. Putting a "weak link" anywhere in the chain stops the whole process of getting the air in and out of the engine effectively.
Jerry
