which carb..?

[bulldawg art]

Looking to change to a different carb set up on my motor. Holley HP 950 was recomended. I checked out Summit and they have two different HP 950's. Which one do I go with? Ultra series or the pro series? There is about a $300 difference between the two.

[BrendellaJet]

I have the lesser of the two(pro?) I think the ultra came out later and has the billet metering blocks...Either one is a nice carb. whats it going on?