OK Seafoam, 1/2 can to a full tank of gas normally, but a full can to a tank of gas is a good idea for extremely gunked up carbs. I would first sample what is coming out of the bottom of the fuel tank before you go any further, it may be contaminated with rust, moisture, etc. Also, a new fuel filter may be in order as even though your fuel pump is working you can lose pressure thru a clogged filter.
No spark is not necessarily the TCI, there is a lot other causes, but it could be the TCI. No, an '85 will not work on the '83 as the '83 has a TCI that only works with that particular year. It has to do with the vacuum advance circuitry being exactly opposite of the rest of the years. That has to do with where the vacuum is sampled from on the '83 as opposed to the following years. The vacuum is 180 degrees out of phase so when you need the spark to advance it will retard, etc...
Once you get it running and run a tank full of seafoam treated gas plan on replacing the plugs again as a lot of crud will be broken loose and it may foul out your plugs...