I have one laying around for my 1680 and never installed it so i can't tell you anything about the dimensions
and if it fit's properly.
One thing which struck me was the pearl. IMHO you have to change the pearl cause it's way of.
Currently i have a gen insert on my 1680 and a PMWF with a Ofrei pearl on my 1665.
To be honest the PMWF looks real great and i don't see a lot of differences between them.
1680 with gen insert
1665 with PMWF
And a comparison shot with 3 of a kind ( insert on 16610 is also gen )
Hope this helps you to decide which insert to buy.
Carpe Diem
Cats