It´s Sandy Block on bass, according to the MilesAhead Charlie Parker Discography.
When in the Ornithology world, things get to discographical matters I tend to stick to the Gospel according to Robert/Leonard/Norman (Bregman/Bukowski/Saks, that is!). In their invaluable Charlie Parker Discography, they say it's Jack Lesberg on bass.
I'ld hate to be told this Gospel is inaccurate