Good morning, Dani~
As others have said, the question here really boils down to polyester or epoxy.
Polyester is appropriate for boats made of fibreglass. For wooden boats, though, the resin should be epoxy.
WEST system is wonderful stuff - but it's not the only epoxy system on the market. There are many other lines, most of which are much less expensive. In your neck of the woods, I have been very happy with U S composites for several years now.
Epoxy product lines typically include a variety of resins and a host of hardeners, fillers and additives. Each has a special "best use". I recommend your friend chat with the tech experts at whichever company he/she goes with. (And, yes, products from one company can be used with products from another. I use US Composites resin but have a few WEST fillers and additives on hand.)
If all of the existing 'glass is being removed - down to bare cedar - I would envision first thoroughly sanding, then rolling on a soaking coat of epoxy resin, then filling and surfacing imperfections after it cures. THEN, the re-glassing would commence.
One last general note: Epoxy resins must be mixed with their hardeners precisely at their specified ratios. I use graduated mixing cups so I can get the 3:1 (resin:hardener) ratio I use most of the time. Most suppliers also offer calibrated manual pumps that dispense the specified ratios.
Hope this helps!
SJS