Has anyone put the vibrato for a 325 on a 350v63? It seems like a direct fit. Is it? Does it totally kill the sustain and render the tone into the weasely territory?

Yep, been there done that.

The strap pin hole is in a slightly different location so the tailpiece sits up a bit high and does not quite cover the holes left from the trapeze mounting bracket.
Also I think there is ever so slightly less sustain, probably because the break angle of the strings over the bridge is reduced compared to the trapeze tailpiece.

There is at least one after-market replacement tail-piece bracket for the Accent that makes it sit flush to the top of the guitar and covers up the screw-holes from the trapeze and "R" tail-pieces. I fitted an Accent and said bracket to my 330 and couldn't be happier. It's not capable of Floyd-Rose style dive-bombing, but it works nicely and looks great (which may be important for some).

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As I get older, my music gets softer and my shirts get louder....