I've finally been able obtaining an original jiffy for my '88 model F1 that originally has a center stand.

Question:
Does the center stand has to be removed in order to mount the side stand, or can both be installed simultaneously?

All I can offer is that I do not recall seeing any F1/F3 with both a centre stand and side stand fitted at the same time.

That said, I look forward to learning what you discover.

I put both on my F1 and had no problem with the fitting, I extended the foot on the side stand and they both work fine

That's grand. Thank you.