[Mr Beau]

I would argue that compression has a pretty small impact on the size of carburetor. The compression doesn't affect the breathing requirement of an engine like port sizes and camshaft do.

In my experience with sidedraft Webers (which are essentially the same as IDA's), the choke size has the biggest affect on low speed driveability vs power. On a 2L engine with 40mm Webers, 36 mm chokes make good power up top, but are unsuitable on a street engine. Conversely, 28 mm chokes make good bottom end torque but literally choke the engine up top.