Try to get a TQ from anything before 1980. That way it will have the vacuum port already installed, and will hook up to a distributor with a vacuum advance. The standard distributors for ELB cars didn't have a vacuum advance, so you will need one of those as well. The carb will need a rebuild, either on your own, or from a good rebuilder. The distributor may need one as well. Depending on the local junkyard situation, much of this can be had from Dodge standard sized pickups (as opposed to the D50) of the same approximate year range as your car, as the trucks didn't get ELB, or at least, not may did. We also did get 318-4V J bodies in Canada from 1981-1983, while in the US, the only 318-4Vs were in California, the rest of the US got 318-2Vs for 1981-1983. Also, don't get too hung up on the TQ models, in the hands of a somebody who knows what they are doing, either the 800 or 850 CFM models can be made to work well on a 318, and just for the record, the 800CFM was found on small blocks all the way to some 383/400 big blocks, and some 850s were used on small blocks (340s and 360 higher performance models).
Kostas