I do not still have time slips from 35 years ago. This is all coming from experience not book reading. The Performer (not Performer RPM which is later issue & a better manifold) was available at the same time as the CH and DP series intakes as an upgrade. Much like the LD series was available at the same time as an upgrade from the small block Performer. Or as in the now days the Std. Performer (which is still produced) to the RPM.
Do what you want.
PS: they worked a lot better on the dirt tracks too. But who cares those days are long gone. This is all coming from experience not book reading.
AS for the horses we have many championships, Association ROM's, high points, and state awards there, so they have been good to us.