Your LIM is the theorised less desirable for the 92-95 range. The plug is for a second CTS which would be for a temp gauge. The plate is used for coolant routing (they couldn't make the passages do what they wanted with out an access point there).
What'* the deal with those gouges? Do they go all the way through? If they are just cosemtic blemishes and don't puncture all the way through or push material into the shaft bore, I'd leave it. You can always put your nosedrive on it when you swap if this one is damaged.
Refresh me guys, did the walled LIM show up on the 93 or 94? If 94, then that LIM was not on the same engine the SC was, just so you know. The walled LIM is the less desirable one, which is the one you have pics of.
Flowbench data hasn't been done. He was shipped overseas.
Rule of thumb:
The sharper the turn, the worse for performance (flow). Walled LIM'* force a sharper turn and create dead spaces between the ports. These cause turbulence. Flowbench data was intended to prove HOW MUCH of an improvement the non-walled was, not WHETHER it was. Same general rule applies when planning a sprinkler system for your front yard. Fewer 90 degree bends equals more flow.