Those V4's can take quite the beating but if you wanted to 'spruce' it up a little here's what I would do.

New fluids (oil/coolant/brake)
New plugs
Sync throttlebodies/carbs
If the brake lines are the original rubber lines I'd replace them with ss braided lines (rubber lines have a shelf life)
New front pads
Inspect the chain and sprockets (find the service manual for the bike, it should explain how to measure the chain to see if it has stretched out of spec)
Replace the air filter

That should be enough to put a dent in the pocket but get it back to running healthy.