Thanks! It is a prized possession – many good memories.
Yes, I had to go with rigid in order to preserve the original geometry of the bike.
The RockShox Mag 21 that came on it was either 48mm travel (standard) or 63mm travel (with the long travel conversion installed). The axle-to-crown measurement on modern suspension forks, even 80 – 100 mm, is too long for the frame IMO.