To not mince words, the circuit
was designed wrong -- it doesn't allow for the full variation in parameters of the components chosen, and now you must, in effect, create your own part, or locate a part with tighter specs that's otherwise equivalent.
JFETs are largely distinguished by junction size, and by process variation (which gives the equivalent trio of Vpo, Rds(on) and gfs variation together). (Voltage rating counts too, and polarity, but with >40V and P-ch parts being almost as rare as hen's teeth anymore, this is secondary.) JFET part numbers are further distinguished by selections for various parameters: Vpo or such; Rds(on); small signal or RF parameters; or noise (at LF or RF). That's about it.
So, basically, what I'm finally getting at is, by receiving loose parts and sorting them by Vpo, you're effectively making your own internal part.

Individual part qualification testing is terribly tedious, but it can certainly get you through your run of a hundred, until circuit changes can be made.
Tim