I recently put a Amazon Carter replica on my 1979 d100 and it seems to be running very good, I know some people are sceptical on using them but seems good.
I have run 1972-1979 318 trucks for years, and the carb that has worked best for the longest for my 72 W200 318 has been a Motorcraft 2150 I got in a conversion kit (that is currently sold out on EBay)......I hope to get another someday for my 75 D300 dump truck. I did OK with the Carters but they would all eventually suffer from mid range bog and idling issues....but truthfully, that was all before I found a local source for ethanol-free gas.