The most helpful feedback has already been given, as far as I know. What struck me was what looked to be actual holes in the floor pan, as already noted. And the fresh undercoat covering everything, as already mentioned.
Most of my comments are of the "it seems curious that.." rather than things to be on the lookout for.
Overall, this car did not seem like it was well prepared for sale. There is new paint and undercoat, hiding who knows what, but the car seemed otherwise very tired. It is almost like they did the minimum necessary to get the car to passingly presentable and threw it on the market. The inconsistency just gave me a bad feeling. Not much help there in what to look for, but overall gave a feeling of just something is not right.
The engine and bay were totally gringy, they had to scrap crud off the valve cover to show the Sunbeam sticker, the oil filter seemed to be just floating rather than tied down and mounted properly, etc. It is almost like a barn find condition in that area, with a new aircleaner and element.
There also seems to something amiss in the trunk area. Curious how it is all stripped and the spare tire hold-down mount has been changed to a stud. Every Tiger I have seen had a threaded hole there. The welds on the hold down "cap" also looked quite different from how they look in my car. Also the vertical face of the forward wall seems to have some irregular spot welds that are not on my car. Cannot see if there are the hold down brackets for the false floor, which is missing. Would appear some repairs have been made, and if so, I would want to know why. Repairs are good thing, one just wants to know the full story. The missing false floor and tank area covers are issues fairly easily dealt with, but are things to be recognized as fix-up expenses one would probably want to address.
The interior looks very tired, although it has new door panels. Again, not the sort of thing that commands a premium price. Also they are attached in a curious way with the pressed in buttons. Not necessarily a bad thing, but clearly not standard and one wonders why.
You raise a very interesting point about the differences in last digits of the JAL and the VIN numbers. They seldom if ever exactly match as far as I know. However, the gap here seems unusually large. I bought my car new in 67 so I am pretty confident about it and it has passed a TAC inspection I finally got around to a few years ago. The number gap on my car is 17, which Norm Miller once told me seemed a bit on the outer limits. Here the gap in numbers is 68. Again, curious.
As far as I know, the TAC process a lot on finding evidence of things reflecting construction techniques as undertaken by Jensen in the original build process. I am not sure if the VIN and JAL figure a lot into the process.
I would say the more you can look at Tigers that other people have the more you can develop an eye for what seems at least worthy of further inquiry.
I also like Randy's comment about wounded drivers and toolboxes. Very fair perspective. At some price, this car would have been an acceptable buy. As noted by Hans, it seems to have gone beyond that point, at least IMHO.
Sorry for being so long and maybe too chatty. Hope there is some value in all that.
Gene
