hard to tell from the pic what's going on beneath the carb pad? and no info from the Offy catalog either, 5183 is listed on page 21/52
http://www.exeterautosupply.com/Docs/Offenhauser%20catalog.pdf
might have to wait till you have it in hand to see what that intake's doing, there may* be a guy around that might know though, and he'd probably be able to suggest what carbs to use also... let's see if he'll pop in...
"Enlightened statesmen will not always be at the helm" ~ James Madison
