What have you got? A sweet parts bike or a shitload of work. Take your pick. You did find a great Forum to get her back in order! Welcome!
Sweat equity can solve the appearance items. Cold, hard cash can solve everything else. Which do you have more-of, time or money? Go that route.
I would say, after a careful appraisal for structural and running issues, make a determination about what you want to do. If it runs fine, and your inspection shows that the chassis isn't weakened by rust-through/rust-out to the point of structural failure under use, then if you spend the time on it, sure, you can bring it back.
You have to look at what your needs are. If the engine is suffering from the common worn shift dogs for second gear, causing it to jump-out of second gear while under load, you can try to cheap-out by only buying those parts which show wear, the shift dogs are an integral part of that gear, and the mating gear.
A better course of action would be to get the gearset undercut, after replacing any worn gears, and replace the shift drum and shift forks.
If the fork tubes are corroded where the seals are, you will have to bite the bullet and spend $ for a good used set of downtubes or buy replacements from a USA supplier like
Forking by Frank. Last time I checked a USA price for a pair of downtubes was $300, maybe more now. You cannot do anything to your tubes to 'bring them back' which is cost-effective, except replace them.
The rear shocks probably have corrosion on the shafts and have the jounce/rebound capabilities of a 20-euro pogo-stick, and will need replacement. You could probably find a decent used pair to get you back on the road, but you are better-off buying some quality used replacements such-as Hagon, Progressive Suspension, or another purveyor of replacement shocks. My advice is to stick w/a stock 13" length, measured eye-to-eye, on-center. Shorter ones cost you travel, will make it easier to ground-out on corners if you are an enthusiastic cornering-devil, and are not as comfortable for the long-haul. People replace the stockers with up-to 1.5" shorter, indeed, I have a pair of 11.5" Progressive Suspension 440's, like new, just sitting because I don't want to give-up the cornering clearance.
Things that you would have to replace on any bike given wear and normal use, those are costs that you will have on most-any bike, given enough ownership time, like tires, brake pads, batteries, coolant, oil, brake fluid, and maybe either master cylinder rebuilds or replacements for F & R brakes, and the clutch master and slave. Those costs are a wash, as you will have them with any bike, eventually.
Appearance is highly-subjective, and there is something to be said for having a 'rat-bike-appearance' ride which is mechanically-sound and maybe even modified to provide better-than-stock performance. Nothing
gets a guy's goat than to soundly-defeat him with a ratty-looking bike.
"How could that pile of &^%%^$#$^!* beat me, doesn't he see I have a 2013 Tardive Dyskinesia 600 Sport, as-ridden by that famous Italian rider to great international success?" Looks can always be addressed, after safety, reliability, and your budget are addressed.
I bet a pound-to-a-pauper that your bike spent its years close to a saltwater source, like the North Sea, or the Atlantic Ocean. That's the kind of appearance you acquire from salt-laden air. Nothing that sandblasting can't remove, once you properly-seal the engine. See the pic of my engine before and after sandblasting. I did it myself w/a 20-lb. pressure canister and a 60 gallon 220V air compressor.
So, tell us about its running capabilities. I may have missed that description. First order of business is to see it runs, shifts, and doesn't leak or overheat. Then you need to make a list of what needs to be done after a thorough exam of its bones. Price parts, labor, and total the costs, and see if your financial commitment matches the number this bike will take from your funds. You may decide to start w/something less-needy, always good advice when dealing with mechanical equipment or women.
Post on here and see what we can do to help you. 
unk:
Here are some pics to encourage you. The dated pic w/the blue tarp in it is my bike being slowly-brought back to use after an extended period of non-use. The one where I am polishing the bike, it was 1700 miles on the odometer about then and a year-old (pic is from 1993), you can see it has a paper tag (the temporary one they issue you here until your new metal tag arrives), and I was much-younger and thinner then! I'll tell you that I have spent over $4000 in parts, labor and repairs since that pic with the blue tarp was taken (Dec. 2011), nearly two years-ago, and I am not done yet. The last two are pics of what it looks like now, taken last month. 
