I remember dealing with something like this a long long time ago. I'm not sure if you can modify the float bowl, you may need to acquire that type of float bowl.
Way Way back on my first 57 Chevy, I had a Holley I acquired from a local junk-yard. It had the center hung float bowls, and fed from the drivers side, then had a tube from the front bowl to the back bowl on the passenger side. I think you might need that same type of front bowl.
No, there are two feeds to it. Think they call it a 4150. I also have a 600 that has a single feed and side hung floats, this one has tube feeding the rear.
yup, mine was that type too. The tube it had to feed the back bowl was basically in place of the standard chrome holley dual feed line. So basically the front bowl had in inlet on each side, and the rear bowl only had an input on the passenger side. They were center hung bowls.
What I did was use a chrome holley dual feed setup, and then plugged the drivers side inlet on the front bowl.