Hello I'm back, and now I'm preparing to tear into my transmission to settle the problems it has been suffering from for some time now. First off, the description.
1984 Chevrolet Camaro
2.8L v6, rebuilt and functioning very well
700R4, untouched from factory

Now for a little history on it..
Known issue of leaking cooler line has caused numerous low fluid conditions during the four year operation before it was parked to be restored.
Computer is no longer hooked up to any sensors on the engine or carburetor as all parts involved have been replaced with aftermarket parts, mechanical distributor from an 82 blazer, aftermarket sensors for digital dash panel, full manual 4bbl carburetor, etc.

Finally the issue, which has led me to the creation of this post. I'm really hoping a guru of some kind out there has a quick answer for me.
Transmission does not transfer engine power in manual selection of first, second, or third gears. Park, reverse, neutral, and automatic drive all operate as expected; meaning that when I put it in park it doesn't move. In reverse, it goes backwards with ease. When in neutral, it can drift but functions like park with the transmission disengaged. When in drive, the engine power is transferred with no problems through all gears, it starts in first and shifts to second, third, and fourth at the appropriate times and RPM ranges. TV cable functions as well and will hold the gear longer if the pedal is pressed down further as it should. The only time the transmission malfunctions is in first, second, and third, and only when manually selected by the shifter.

When these gears are selected manually, you can rev the engine between idle up to 6,000 rpm and the result is the same, it acts as though the transmission is not engaged. You can gain up to a very sluggish 2-3mph forward motion, but nothing at all like it is in drive. It's as if, if I were to describe it best, that when you are in drive your hands are opening a pickle jar with gloves on, and when you manually select the gears with 1st 2nd or 3rd, its as though you've been soaking both the jar and your hands in motor oil for several days, a near complete slip situation.

So now for my questions. Anyone ever see this before? I know that the torque converter lockup is controlled by the computer, and is the only electronic component on this transmission, could it be related? What system or systems could most likely be the culprit, meaning do I just need to check the governor, valve body, or do I need to fully pull the transmission and start replacing the internal components? I'd like to know what/where I should be looking before I pull the transmission and jump in face first blind folded.

Any information is welcomed and appreciated. My knowledge of the transmission is limited to a GM tech service manual and the basic operations of transmissions you can google and research from a desk.