Nice - I guess you got it fairly cheap!
I rode a CBX1000 (The 6 cylinder one) a long time ago during a VFR club visit to Germany where I switched bikes with a German owner there. A bike from around the same era. Suspension was soft and wallowy at the mere sniff of a corner and the brake woefully inadequate. So I think these things may be the first that will need attention once you have it up & running. Tires too of course.
Old fuel inside the tank is better than none!
If available, get carb gaskets / o'rings and fuel tap seals too. Take the fuel system apart and clean everything. Acetone gets rid of the varnish. I used cotton buds. The best way would be to clean with ultrasound, but you'd have to find someone with such. A carb piece clamped to something sturdy and a steam cleaner does the job - as does a jet wash...
For now, rebuild the brakes and fit braided lines if you want better feel. Brass brushes on the end of a dremmel are great for cleaning out the recesses for piston seals.
Looks like it'll be good to give it a paint job. If you get that far, then you'll probably be looking at replacing the front end with something more modern, new brakes and more.
BTW, once I do my RC51 front end conversion I'll be selling a set of reworked VFR750 forks (perhaps too short?), triples, Harris 6 pot calipers with a CBR1000 master cylinder + front wheel, discs, etc. Old technology, but it still works well. These calipers were able to lock the front wheel at 50 mph given a hard enough tug (I saved those
moments), so they're still good. If they're of interest (no rush - I'm not doing this work for a while yet) I can take some measurements.
Euro RC51 SP2: HRC WSB Ti Hi-Level, T1 Airbox & Snorkel, PCIII, Dymag CA5 Carbon Wheels, Ti64 Spindles (F, R & Swing Arm), Mori Link, Maxton GP7 Shock & Ohlins 832 Forks, Brembo GP Calipers & SBK narrow track (F), Braketech Disc (R), Brembo billet Underslung x 2 Brembo RCS, Tyga Triple, 7075 Stem, Probolt Titanium all over, Babyface rearsets, MR Complete Carbon Lineup, Custom Undertail & CBR 1000 LED, Watsen LED Indicators, Harris Brace, Giles clip-ons, Corbin seat, etc. 2013 BOTY.