Moss 'Box Swap Value?

I’ve been dickering back and forth online with a local guy who has a motley collection of old Jag parts for sale. Mostly '60s sedan stuff. He didn’t have an early water pump for me but mentioned he has a JH gearbox with bell housing. The gearbox has been partially disassembled though he says it’s complete. That would be a nice-to-have but not something I need. So I’m not interested in shelling out money for it, but mentioned a '120 I have came with a manual Mark 2 gearbox with overdrive that’s still a complete assembly and gathering dust in a corner. He was quick to reply so I gather there’s some interest. I’m thinking of proposing a straight swap. Does this sound fair? Any thoughts on value here? Both of my '120s already have JH gearboxes. Thanks.

Depends on what is meant by “partially disassembled”. Make sure every single part is there and not broken.
Why was it disassembled? If stuck in first gear, that can be solved.
Also a JH box could have either a XK or Mark V bell housing, and may be set up for either LHD or RHD.
Since the Mark 2 box is of no use to you, but is desirable among Mark 1&2 people, I would go ahead and investigate a swap.

As it’s here in the SF bay area, I’ll go out on a limb and assume it’s from a LHD car. Didn’t think to ask that when I spoke with the gentleman a little while ago. From the attached pictures, it looks like it’s broken down in to major blocks of parts. We’ll see. I’ve already tentatively agreed to a straight swap so it’s not like I’ll be out any major money. And as he’s heading south past my house to Monterey with his wife next week: no worries about logistics. Attached are pictures of the gearbox in question. Please note that the shifter lever seems longer than what I’d expect to find on an XK (?)

It appears to be JH7647. The long shift lever is for Mark V and VII. Likely it came out of a 51-52 Mark VII. I can use the lever, will make you a swap for it. What do you need that I might have?

That’s very generous of you Rob. I’ll PM you after I actually see this 'box in person. And as the picture cuts off the shift lever, I’ll try and get a better one to you. Thanks.