It looks as though there may be enough room left between the carbs to use a metering block in the secondaries as long as you stayed with the side hung float bowl. Just like the six pack set ups. Look at the mechanical carbs, they use a side hung float bowl and the rear fits with a metering plate. As for jetting, yah, it would suck to set it up but it's very doable.

BTW ... great photos Andy!!! you should do some side work for a magazine