Hi Jake.
Repair pics of the Carvin don't exist, that was done in the late 80's, but I can take pics of similar repairs (not in the middle of the neck though) this weekend.
Basically You do a very low angle long scarf joint.
The mistake I made, was not to remove the FB completely, the end result was far from straight.
I didn't have anyone to learn from, so I made a lot of mistakes.
One just have to learn not to be afraid of making mistakes.
Even though my main goal in my teens was obviously to get playable instruments for as little money as possible, improving my skills on cheapos in order to be able to make money later on with repairs on more valuable instruments wasn't far behind either.
I'd look at that guitar as a possibility to learn set neck repair rather than the possible monetary value of it.
I'd count the hours as the cost of learning something worthwile as well, to be paid for later on.
You're relatively young, and the demand for skilled repair persons for musical instruments is increasing all the time, so even though I wouldn't necessarily advice instrument repair as a career choice, I definitely would encourage it as a hobby.
Rather lucrative hobby at that no less if You're good enough.
If that guitar came to my bench, I'd remove the FB, then steam out the neck and I'd make (or fit a pre-made) a new neck to it.
I'd still make a bass out of it though, I'm wired funny that way

.
Regards
Sam