Hi Chr1st0phe,
From the pics you've shown so far, the rear triangle, brake hanger and dropouts look very very similar to those on my 1995 KHS TiLite's. Your frame has rear mech cable bosses in a different place on the rear triangle to mine though and your frame appears to have a rear mounting clamp, (and therefore rear hole/cutout?) on the seat tube wheras my TiLite's don't have a clamp welded onto the seattube and the expansion cutout is at the front. Other than these 2x differences it looks really similar to my frames.
Got any pics of the cable holders on the top tube?
HTH
James