Is this bona fide

Sure Holley made them with the dual line float bowls. They still do. They used to make them like yours with the choke tower and all but they discontinued it. You can still buy them from Summit, albeit with no choke tower.
Holley 0-80507-1 Holley 4150 Classic HP Carburetors | Summit Racing
Now, whether yours is "original" or not is another thing altogether. You should be able to get the numbers off the float bowls and tell.