I agree with Jeff. O-1 would be my first choice for a forged chef's knife. Then 1095 and 5160.
I think O-1 would make the best kitchen blade but be careful when you forge it not to overheat it. O-1 tends to go red short real easy and gets a "cottage cheese" looking effect on the blade when it does. If it does that to you, just go ahead and start over. 5160 spring steel is much, much more forgiving in that regard.
Just my .02 worth....GaryB
p.s. This is something you probably already know, but for a blade that's going to end up that thin, I would forge it thick and grind it thin. Warpage could be a real problem otherwise.
[This message has been edited by GARY B (edited 06 December 1999).]