There's always the opportunity to pick up another Rickenbacker that shows more wood (so to speak

) next week or so...
Original guards may not be available online, but PM me if you want a correct guard.
You mention the "New Jersey butcher". With all due respect, don't compound his error in parting this out by changing it in any irreversible way. The wood on these was usually quite plain...not too much character, so covering it up with the strong graphic element of a guard is part and parcel of the style, character, and DNA of these early solidbodies.
The fact that you began thinking about a 330/360 type guard without looking carefully at the body (because it's obviously not compatible), gives me an impression that you might be impulsive with regard to rebuilding this instrument. Again, Paul, with all due respect, consider the history of this guitar and remember that history only goes one way--things get older and as they age, the nice ones get rarer (MUCH rarer), too.
I've restored close to a dozen of these beauties (TWO from the NJB) and would not dream of irreversibly modding one. There are ten in my own collection, only 2 of which I didn't re-do. Here are some photos to fire you up about how sweet these can be...
First off, a rare lefty from 1957 (sort of the beginning of this style...)
Next, a '67 very similar to yours in factory JG. This one came from the NJB.
In progress:

(Just look at that fretboard wood!!!)
...and finished:
Another '67--this one a standard-scale 425 with factory vibrato. This one is stock, but has black hardware and pickguard, all reversible:
Finally, here's a lovely late ES-16 in FG, similar body shape to yours, in FG. This one is 100% original:
So, get acquainted with that big piece of acrylic and learn to appreciate it. There's plenty of time to find one of the "traditional" Ricks--they're always available!