You can do what you like, of course, but that's a lot of money to throw at an '80s mid-range road bike. You might have a nice example when you're done, but you must question whether it is cost-effective to do so when what you'll have is a repainted, upgraded '80s mid-range road bike.

Second look at that crank tells me it will NOT accept an inner third chainring, so the recommendations for different freewheels are the best way to proceed.

Here's one in another thread, with some upgrades:
http://www.bikeforums.net/classic-vi...i-special.html