some part of our psyches is on the same wavelength Simon. I have lots of little Merbau blanks. i found three with a common grain structure and what i think i will attempt to do is laminate these together along they matching grain lines a create a sort of a raised Merbau plug that I can laminate into the front, and then blend to the contours. It will sort of tie the differing woods together some what.
Or I could just throw body filler in it like Dedman says and fire a copper accent plate over the top.
Either way the FrankenWashie reboot is turning into a Saga, though I have a while to go to rival Doc's Epic "The Gold Standard Strat" thread.
Stay tuned intrepid Adventurers! This is liable to get SILLY.