Well it's two things. First off, the bass was a gift and I don't want to sell it. Second, the resale value of a Mexican j bass is probably like 300 bucks. For the pickups, wiring harness, bridge, new maple neck, and fresh strings I'm looking at 700 total. So for 700 I can have it exactly the way I want it or sell the Mexican for 300 and pay for a body....then throw the 700 into a neck, pickups, wiring harness, bridge etc haha. If the resale was higher I guess I would understand but a Mexican jazz doesn't go for much used.
Well, figure you could get a body for 100-200 dollars so you could come out a bit ahead selling the whole bass. If it sells for 300 and you find a 100 dollar body, boom! 200 extra for your other parts.
However you could also sell your current neck and all the other parts and make about the same back. The only problem is it's a hassle, you don't always get what it's worth when parting things out, and you might be waiting a long time for it all to sell. There are some businesses that make money parting out Fender instruments however they have the ability to sit on their inventory for months on end waiting for buyers.
Of course, all up to you. No need to defend yourself to us!