One thing you might want to do if you're not scared of basic wiring is mod the circuitry to allow the coil tap to be selectable in position 4 as well as position 5. By default pos4 is middle single coil and tapped humbucker ie bridge single coil always. This is to balance the pickup resistances (ie signal strengths). However with a simple snip and a bit of insulating tape I think you can make this tapped or untapped same as possible with position 5. I will dig out the wiring diagram and confirm.
Edit: I've looked it up in the Service Manual.
I was right. What you need to do is (depending on how it's been done from the factory):
either
a) If the white wire from the humbucker goes directly to the pins on the tonepot switch (not the potentiometer lugs, the DPDT switch below it) then cut the adjoining wire going from the same lug on the tone pot DPDT to the 5-way switch (it will land at the switch in between two empty pins).
OR
b) If the white wire doesn't do go straight to the tone pot but goes to the 5-way switch 1st, and from there a separate wire goes to the tone pot switch, then you need to remove both of these wires from the 5-way switch pin, but leave them connected (and wrapped in insulating tape) to get them to still travel to the tone pot pull-out DPDT switch but now disconnected from the 5-way switch.
OR
c) (not recommended) Alternatively you can cut the black ground lead going to the 5-way switch, but this leaves the switch ungrounded so this option is not recommended.
This mod prevents the 5-way switch shunting the white humbucker lead to ground when in positions 2,3,4 and therefore gives the user the option of full humbucker blended with the mid coil in position 4 (positions 1, 2 and 3 do not connect the hot lead of the humbucker so this makes no difference to those settings)
(As an aside the white lead is actually a pre-joined combo mid lead from the two single coils in the pair. I did a bit of surgery on the stock pick-up when I swapped it out and if you want to convert it to a 4-lead humbucker you can, but there isn't much wire to play with and you'd probably be better just buying a new 4-lead pickup to start with as you have to butcher the wax tape barrier to get to them, and the wire is rather thin behind there)
) Enjoy it, it's a great instrument. 
