GM G body power steering box issues

[68Malibu383]

Hey all,

I have a '68 Chevelle with a late 80's Monte Carlo SS steering box. Been running that combo for about 20 years using the Lee Mfg fitting adapters and a stock reman '68 PS pump.

During normal driving, everything works fine. When autocrossing, the pump wines and steering becomes jerky. Last time this happened, fluid spewed out from the PS pump cap and sprayed my brake rotor.

The first time I autocrossed the car, this happened and Lee Mfg had me remove a restriction at a fitting on the pump or steering box. Something about the fluid not returning fast enough to the pump or fluid leaving too fast?

I've since changed both the box and pump and cannot recall what I need to do to fix this. I've called Lee Mfg and we played phone tag for a while and now when I call (several weeks ago at this point), the phone line is dead.

Anyone know where this restriction is?