Here is my humble "reasoning."
Frets: very significant wear on multiple frets visible in photos. Refret might not be needed if you like very low frets. That could be OK if the neck is very very healthy. The chances of that in a '74 are low, in my experience.
Truss rod: The nut looks like it has been turned a lot (in and out), the neck hole is boogered. The photos are careful to avoid any side shots or fret plane views of the neck. Red Flag, IMHO. Sellers like this are not usually stupid, just greedy (check the price).
Early and mid 70's P-basses are prone to a hump over the pocket which often eats up truss turns, yielding a shot truss rod. Also, most P basses of that vintage have some degree of asymmetry to the relief, i.e., you can't get a consistent action with normal relief. The seller mentions "high action," and blames bridge screw corrosion. Sorry. That is not an acceptable situation. A seller of a vintage bass MUST remove such obstacles to assessing the health of the neck. The only reason for not doing so is to hide an unhealthy neck that needs serious attention to get it to set-up properly.
I must admit this is all just conjecture, but it is based on having a fair amount of experience with 70's P-bass necks (5) that all had these issues to some degree. For 5K, a buyer must demand the seller not hide problems.
A good refret is ~$250. The cost of addressing truss rod issues: $unknown and not certain to be fixable. This might mean you are back on the market looking for a suitable neck, which puts you right back in the same situation, only worse...:scowl:
A neck is is much easier to evaluate on a strung bass than as a part, so in a way, you are worse off searching for a neck alone to upgrade a sick vintage bass. Sick vintage necks do end up on the market mounted on the less desireable old basses, IMHO, but are often sold "AS IS" as parts. Can you tell I have been burned???