Have you decided on your cockpit setup yet? If you are doing a drop bar conversion you will need brake levers, bars, cables, and bar tape at the very least. The shifters and derailleurs could be used with a drop bar setup mounting the shifters to the tops or on the ends as a poor man's bar end. If you are going with a flat bar or trekking bar, the parts will move right over. I personally think if the frame fits, you should go with it to see how you like the ride, especially if doing a drop conversion. Upgrade later if you need to. Lots of times you can pick up a complete mountain bike with a nicer group for cheap on CL, even if it's too small you're just buying it for the parts anyway.

Another consideration with vintage MTBs is the rear spacing, many times it's 126mm or 130mm. If you are keeping the wheels, it may limit the number of rear cogs and therefore the shifter choices. Friction bar ends will work with just about anything so are a good choice. If you want to go more modern, you can cold set the frame to 135mm to use standard freehub wheels and more rear cogs. In any case, I would check out the spacing before I bought anything for use on that frame. Good luck.