Do you know what you're gonna do with all the switches? Here's what I'd do:
3 vertical switches on lower bout- on/off for each pickup
2 horizontal switches on lower bout- phase for neck and bridge pickups
switch on upper bout- rhythm/lead
rollers- volume and tone controls for rhythm circuit
regular knobs- volume and tone controls for lead circuit
switch on the same plate as the regular knobs- strangle switch for lead circuit
Also, it might be cool to use 250k pots for the rhythm circuit and 500k pots for the lead circuit. Another thought I had is it might make your life easier to simply use an all inclusive pickguard that contains all of your electronic components instead of getting all of those little metal plates custom cut (a la Jazzmaster). Additionally, the Jaguar type slider switches might be easier to find than the ones shown in the picture. Oh yeah, and the trem appears to be a standard mustang trem with a fancier baseplate, so you could prolly just buy a mustang trem off ebay and use that. Although imo a jag/jazzy trem would flow better with the aesthetics of the Marauder, and, from what I've heard, are all around better trems than the Mustang trems; So I personally would go with one of those (plus they have the advantage of being able to function as a hardtail). After all, the Marauder never made it past the prototype stage of it's development, which imo puts you at liberty to make a couple of changes.... Anyways, I hope you find this post at least slightly useful.
(PS sorry for offering all the unsolicited advice, I find Marauders EXTREMELY interesting, and have a hard time controlling myself)