Suzuki 2 Strokes

Hi folks,
I have what I believe to be a 1971 (and also a second 1970) T250. Both have been in pieces my whole life and I'm quite keen to try and put one together. I'm quite a novice, so bear with me.

One engine has one of the front mounts snapped off, so I'll be focusing my efforts on the other engine (and respective frame).

My first stumbling block is the wiring... the frame has what seems to be most of a wiring loom attached, but I can't for the life of my figure out where the battery terminals should hook up to. I found another matching wiring harness, and it has a negative terminal sticking out of the main loom (black and white wire with eyelet), though the Haynes manual suggests the negative should come directly from the Rectifier?
I can't find the positive side on either loom, whether its missing or I'm just not looking properly I'm not sure yet.

I think for now some ideas what I should be looking for would be helpful. I'm keen to verify the main ignition system works before moving elsewhere. I'm not looking to restore for now, just try and fit the puzzle together and get a mostly working 2 stroke bike!
Much of the challenge will be working out what I'm missing, what I've got (everything is in boxes/bags, completely unlabelled or organised!) and what goes where. May ask for photos in future if I get really stumped.

Also regarding the Haynes wiring diagram - can anyone tell me what the Terminal Codes refer to on the ignition switch circuit?
It lists:
HL - headlight?
TL - taillight?
BAT - battery?
HO - ? must be something to do with ignition, given its listed for "on (day)" and off for "parking"
SE - ?
C2 - ?

Thanks

The T250/T350 service manual is here. It has a wiring diagram.
http://www.oldjapanesebikes.com//mraxl_ ... /index.php

HL - headlight
TL - taillight
BAT - battery
HO - hot (ignition, horn turn, signals)
SE & C2 - alternator lighting coil

The bike doesn’t have a voltage regulator. Instead it adjusts the alternator output depending on the load.
The alternator is split into a charging coil & lighting coil. The charing coil is always on. The lighting coil is switched to be on when the headlight is on.

Cheers - that wiring diagram is actually taken from the Haynes manual I have.
Starting to realise the existing loom has been messed with a little. And it turns out this is what I seem to be missing this piece, which is what was confusing me initially. I see it plugs into the rectifier and is grounded there. Doesn't seem to be available so I'll have to make one using the connector from the other loom.