I'll tell you right now, your other work probably isn't related to the transmission issue.
The lokar cable is often a "fix" for people struggling to adjust the factory linkage. I'd wager the previous owner was having transmission trouble and installed the lokar kit to "help" and it was likely set excessively tight to get the car to function.
When you reassembled, the cable likely started loose and that finished off the clutches that were already on their way out.. Couldn't be avoided really, the trans was probably already done so don't beat yourself up.
I got about the same distance (~500 miles) after I bought my car before the thing cooked the clutches. Found out later the previous owner had driven it around for weeks without the trans linkage installed because he couldn't find the right clip...
Hidden damage is a *****.
I hear you on the torque converter. I hope you can find something better than what I have because you already know you want more stall but if you get in a pinch with the wife, I'm sure I can help at least get the car back to running ;)
At least a converter swap is a LOT less work than a cam change!