Like what roccobike said. Just want to add that a fork that is too long will slack out/lessen your head angle. This make your bike less twitchy descending but slower handling in twisty single track (as an example). It will also make the bike climb poorer as your weight is higher and shifted back. I added a mild-length 80mm Rockshock Judy SL to a 1990 Fisher Paragon (not made for suspension at all) and really messed it up. I had to try 3 diff stems to get the climbing back. Personally, i'd keep the bike as is from a collectible standpoint.