I have one more question. Due to the fact that it`s easier to find 410mm TB P2 -specially when you need them to be mounted on a 20" frame and the steerers available are very often too short-, do you think it`s a bad idea to mount the 410mm P2 forks in a 1993 frame? Anthony, what about the geometry? I don`t want to kill the essence of that lovely frame.
Fitting a 2cm longer fork with the same stem and bar would slow the handling down a bit - make it slightly less keen to turn corners. Whether it would be noticeable is down to you, and what kind of handling you like - you might even prefer it. It will certainly make the front end 2cm higher, which your back may well prefer.
If required, you could speed the handling back up again by fitting a shorter stem - roughly on a 1 for 1 basis, i.e., a 2cm shorter stem roughly compensates for a 2cm longer fork. Or a more swept-back bar has the same effect as a shorter stem - it's how far ahead of the plane of the steerer is the line between the grips. The shorter that distance, the sharper the handling.
Hence modern bikes handle well with a combination of a slack head angle and a very short distance between the plane of the steerer and the line between the grips, showing that there's no magic about a 71 degree head angle - it's just one way to get the job done, but there are others.