"Lost art" of old repairs knowledge.

Related to this classic computing, I'm working on a 1987 caravan with 2.2L carb, early type of computer primarily for spark timing advance (still using a distributor but only for timing pulses and a rotor. No mechanicals of any kind in that unit). and three emission vacuum soleoid valves. That's it. I have chrysler's service manual for this caravan but not that detailed like computer numbers and jets sizes in this regard. Every people I talked to does not like to deal or don't want to know with this "ancient" stuff. They rather buy another car or ditch the carb & computer and go with custom injection setup. This is all I have to deal with for time being and do repairs on this old stuff properly requires good information on this kind. Oh, I like this kind of challege and see what it was like in old days. I have contacted two carb rebuilders that specialize in rebuilding, turns out both doesn't know because one buys rebuilt carbs and resells it and sell rebuild kits that all. Other one does their work rebuilding them but doesn't have info on specific jet sizes for particular engine sizes and application use (caravan, Omni etc) The particular carb I'm working with is holley/weber 5220 non-feedback two barrel, secondary vacuum operated when enabled by computer when engine is hot (chrysler's) and were used in so many makers' cars from that era. If somebody have better source of info like jet size etc is much appreciated. Most of troubles is the people doesn't leave them alone, damaging carb in the process and not able to find the basic problem properly and not following the vacuum routing. Emission info routing sticker is right there on the underside of hood (bonnet for westerners). Cheers, Wizard