This is probably a silly question for some...but I honestly don't know?

What size of Gyro is required for an 85 Pro Performer? 1'???

What about headsets? measurements/sizes for OS freestyle bikes?

any insight would be appreciated...

thx.

gyro is a 1".

headset is also a 1", but be careful what you get. old school bmx 1" is different from road/MTB 1". the fork is the same, but the cup size where it fits into the frame is different...

BMX cup=32.7mm
MTB/road cups=30.2mm

also, the bottom race on the fork can be either 26.4mm or 27.0mm.

Thanks mr coasterbrake! much appreciated for the insight.