Just do it! my first Alfa was a Sprint and I still rate it as the most beautiful car I have had the pleasure of owning. (And no I don't think the 156 looks nearly as beautiful)
A 1986 car should be 33 based rather than Sud based so it is relatively easy to modify should you feel the need.
Don't disregard the rust, rust, rust or rust though. It can get to the stage where Fred Flintstone and family would be quite at home- believe me- I have had two sprints and two Suds!
A certain amount of rust is expected (around the windscreen, side windows, top of the front guards, rear wheelarches and hatch) but walk away if you can see the steering rack through the bottom of the bulkhead around the battery and heater- this is dangerous.
Otherwise just look at the usual things, smoky and noisy engines, poor 2nd and 3rd gear synchro, electrics, rear wheel bearings and poorly repaired crash damage.
Mechanical stuff is relatively cheap to fix compared to the body, if the body is good it is worth buying however bad the mechanicals are...
Good luck, I hope you get it!