Having introduced the victim, I am now slowly tweaking it in a probably futile attempt to not perform the radical surgery - replacing the body - that seems almost inevitable. First, I just changed the strings hoping a slightly heavier set would solve both the low tension and low end tone issues. Spoiler - it did not:
Blue Boy (part 2 - changing strings)
Ok, now first let's make sure the neck and body are a good fit, and, even with the generic pickups and hardware that came with the ash body, if it is noticeably fuller in tone. It is:
Blue Boy (part 3 - new body test)
Now comes the work. Although the hardware on the new body is OK, I want to switch it all out with the parts I prepped, aged and installed on the original body (including the EMG Geezer Butler passive pickups, which are very nice). One thing I did notice, besides total lack of shielding on the body (which I corrected with copper tape and ground wires to each pickup compartment, grounded to the main compartment wall) is that the pickup alignment for the bridge pickup is way off (tweaked to the left, so the strings aren't lining up with the rear pickup pole pieces, but OK with the neck pickup).
In all honesty it will probably sound fine regardless, and I have the chrome plate to mount over the bridge and rear pickup anyway so it won't be visible, but can I correct it? Is the problem the pickup route, or the bridge placement? The joys of 3rd party parts...
Lining it up with a template I made from Fender PDFs, it seems the whole body is slightly skewed, but I think moving the bridge to the right a bit would split the difference. Here we go.