Holy cow. For the KA are you talking about a pick and pull or something else? not that is really matters, I mean I have seen some PnP engines do really well, but I would like to know incase I go that route and want to rebuild it before the install.
As far as the carb for the A-series, I will need to see the engine before I know what I need. I have a feeling that the original owner may have replaced the intake mani with something aftermarket or from some other engine, which would explain why the carb won't fit. That or the guy had the wrong carb, but the current owner says he hasn't really had time to check it out. I honestly don't know a lot about these engines, but I know there are a ton of interchangeable parts most of the time and it wouldn't surprise me if the intake mani was something rigged on there.