Which nut for a 1977 Fender Precision ?

Hello, need to restore my 1977 Fender Precision , s/n S880010, 7.25" radius, nut width 41,5 mm. The E string height at the 1st fret is definitively too low ( it have to be 0.559 mm ) and I have to replace the nut. I've found on the market various different nuts but the only one which seems to match is the one from NW guitars. The others are 9.5" radius. Does someone knows if my original nut at the bottom is flat or rounded ? Any help will be highly appreciated...
The closest one i've found is this one... Bone Nut for Fender Precision Bass Guitars Pre-cut & Slotted - 41.5mm

 

Buzzing a little, the bottom of the string have to be 0.559 mm distant from the top of the 1st fret, now it's only 0.400 mm... the bone nut is weared or filed too much by the previous owner...just wish to set the guitar to the factory standards..

 

Good idea this one with the shim, otherwise I'll make a new nut from a blank piece of synthetic bone...

 

Ebony is nice , almost resonating as carbon or brass, but I need to keep the original vintage look

 

Yeah, if the nut base at the fretboard is curved I'll modify the flat nut bone with the sandpaper attached to the fretboard to get the radius, cannot find a curved one 41,5 mm yet, at last, I'll make myself one with a blank piece of synth bone, thnx

 

Done ! Just if someone wants to know, the 77 Fender Precision have a curved nut bottom slot, so I modified the purchased bone nut with the sandpaper attached to the fretboard to get the radius, and filed the string slots to get the desired action of 0,559 mm at the 1st fret. The bass now sounds better, the sustain improved a lot. No E string rattling anymore...