Hi everyone, picked up an old slalom board circa late '80s early '90s. It's a 9'6" Rod Hocker "Concaves" Epoxy jobbie, typical mast track forward and much of the volume up front. It's around 22" wide 12" up from the tail and 24" at the widest point. It has a standard slalom fin of the era...the tubby fella.

I'm 100kg and wondering what max size modern-ish (6 years old) sail can this board take before things go pear shape? Or will it? What else am I to expect if a modern rig is used? Will I find any benefit in fitting a more modern long slalom fin suitable for US Box (old standard)?