If it's unplugged and you are not getting a check engine light, I would say either it has been turned off already as long as he didn't just pull the bulb in the cluster.
It may run ok, who knows. The heads are a major factor in determining what the fuel table should look like. The ECM will adjust it some using the O2 sensor, but the older O2 sensors are not very good (especially the one wire sensors) and the ECM can only adjust it so much anyway.
The heads are also a major factor in the timing table and will require a few degrees less total timing than the old swirl port heads you are taking off. If you end up getting it together and it knocks at WOT, you can disconnect the timing connector and retard the timing a couple of degrees, then reconnect it and that will take 2 degrees out of the entire curve. It's not right, but it should work as a bandaid.