If you want to exchange components, try the D300s with a 16-85. I have experience with that combo and it is super. In addition, you can exchange grips and batteries with the D700 and your 105 becomes a 155VR on the D300s!! Not bad no? Prices are falling rapidly on the D300 occaz so right time to buy.
To be very honest, if you stil lare into Nikon, the smartest move really would be to go with a crop Nikon body, and the 16-85 in that case.
You may think that the other lenses are not the "correct" FLs, but there is no such thing as a correct FL for everything anyway, and the advantage is that you can share and therefore use all of your lenses, if needbe, or if you change your mind about them.
Furthermore, this way it really becomes a backup body. With any other kit it becomes an additional body and lens only.
Finally, operation will be very similar, which means that moving from one to the other is much more intuitive.
BTW, I am biased towards Canon personally, but I think another Nikon would really be in your best interest - unless you hate the D700.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....
