Hight Torque shifts on '87

[5495bb]

My stock '87 with about 65k miles on it drives and shifts great most of the time. But when I push it into higher revs, say 3500 + and shift it up to next gear it's hard coming out of gear but goes up to the next one no problem. It feels like it is "spitting the lever out" and the car can't wait to unload the pressure on the transmission and get into the higher gear. I don't know if it has the original rubber centered clutch in it. My question is if any other readers have the same problem and if so what the fix may be. Any suggestions are much appreciated.