I have some old outboards, some older, some newer, but still old. I am a member at AOMCI, and IMO, although it's nearly in new, unused, mint condition, unless you found someone that grew up using the same motor w/ their father or grandfather, a 1968 motor isn't what most collectors of pristine motors are looking for.
If its running, or can be made to be running inexpensively (most J/E motors can be) and it's in nearly like new condition, I might be interested if I was buying it, to pay somewhere between $300-600. But I am not a typical buyer.
Regardless of the way it appears, you'd need it to be running to get top dollar and for that you'd need to make sure that the hoses and wiring under the cowl would all stand up to use, not just appear to be in good shape and not discolored.
Many buyers would want it to RUN and might like that it's a nearly new 50+/-yr old motor, but wouldn't pay much extra for it.
To the right buyer, at the right place and the right time, it might be 'worth' 3 times what I'd pay.
You can look online and at evil-bay and see that some want extremely high prices for some outboards that appear best suited to being used as an anchor. So go figure..... I am certainly not an old outboard motor pricing expert.
I think it's great that you are concerned about the seller. Perhaps he might just need someone to talk to, and if only another $50 or $100 would make you more comfortable w/ buying it, take him the extra. I suspect having you offer to stop by and chew the fat for an hour once or every now and again, might be welcome too.
