Acetylene Heating Tip J-63-2 with D-85 style Mixer - Compatible with Harris (Tip + Mixer)

i have a harris model 85 with 72-3 cutting head - i am looking for a rosebud tip and mixer -- will this fit thank you?

Why is there a stop nut on j-63-1 that i received? none is shown in the pictures.

Is the d-85 #2 suitable for brazing hvac copper

can this tip be used with propane fuel ?