Depends on how hard you will use the boat. For gentle use (no crashing into things, no hard beach landings, flat(ish) water), even 3 mm ply with 4 oz glass may suffice.
For typical use I'd go with 4 mm ply, 6 oz glass on the outside, 4 oz glass on the inside.
If you use s-glass, 4 oz in and out would do.
All other things being equal, I'd go with heavier ply and lighter glass.