Zenith carb rebuild

[cuda]

I took apart my Zenith carb on my '29 and saw that the fuel valve looks different than what's in my kit. In the pic, the one on the right is what was in there already, the left one is the new one. Is one of these styles better than the other?

Also, is it really necessary to drill out the passage plugs? They never leaked and I'm inclined to leave them alone.