I use cellulose from Jawel Paints and have had very pleasing results as a total amateur sprayer using very basic equipment -
https://www.ebay.co.uk/itm/Cellulose...G98:rk:17:pf:0
Other colours are available...
Jawel recommended giving the fibreglass shell a coat of etch primer before the high-build primer goes on. That's what I did and I had no problems with adhesion or cracking in the four years that I had the car on the road, but I believe a professional sprayer may tell you that the etch primer isn't necessary.
What colour are you going for?