Fuel Tank Selector Valve - I need help please

[Nitebytes]

HI all.
I have a '74 Chevy C30.
She was bought (cheap) from ebay (yeah - I know, it's my own fault, not a mistake I'll make again), and is to some degree a bitsa (translation = bits a this, bits a that) build, for example the front clip is from a c1990s Chevy.

So, knowing that, my problem with the fuel tank selector valve may not be 100% straight forward (although I hope to goodness it is).

It's a manually operated variant, with a simple push/pull knob in the center of the dash. IIRC 'Out' is the right tank, 'In' is the left tank.
The knob is attached to to a cable that runs all the way back to the tank selector valve itself which operates a lever (presumably the lever that selects the tank).

Unfortunately this lever mechanism is seizing up preventing the valve from fully selecting the left hand tank, which in turn kills the engine due to fuel starvation.

I can climb under the truck and manually move the lever across, but it feels very stiff. I suspect it's gacked up (technical term, translation = full of crap) and may just need clearing out. I've soacked it a few times with WD40 in the hopes of freeing it up some, but it's not made a vast amount of difference.

I've looked at the other 'tank selector valve' threads here and from the pictures I've seen, I'm convinced of two things:
1. My tank selector valve is not in a stock location. It's an absolute bugger to get to (I managed to hit my head on the exhaust and the drive shaft trying to get a better look at it)
2. my tank selector valve isn't stock, or indeed anything like what you guys have. (but that may be due to looking at mine form a bad angle)

I did take some pics with my girlfriend's camera, but we haven't been able to transfer them to my PC yet. As soon as we do I'll update with some pictures.

In the mean time, if someone could tell me where the tsv should be located I'd appreciate it.

Mine is located under the truck, on the right hand side, near the right hand fuel tank.
It has 6 hoses attached to it - three above the selector lever arm, and 3 below. I'm assuming that the section above the lever is for one tack, and blow is for the other. but it looked to different to the pictures I'd seen I can't be sure. Again any help in identifying this will be helpful. (As I said I'll update with pictures as soon as I can).

Thanks in advance for your help.