I had that board also, it IS quite heavy, if it was waterlogged there should be quite a bit of discolouring in the balsa rails and feel spongy as the foam dissolves when waterlogged.
I imagine what you have is a fine board, just get out and surf it.
My first post. I love FWs and always weigh my boards -thought this might interest someone..
RF DOM 6'0 - 3020g (gone)
RF SP 5'4 - 3080g
RF spit 5'10 - 2740g
FST Hell 5'10 - 2940g
RF flexfire 6'3 - 2320g!!
FST flexfire 6'4 - 2950g (gone)
Old delam'd/repaired Futura 6'0 FST - 3130g (ornament..)
most PU/epoxy shortboards I've owned have been 2.9 to 3.1 kg. All with tail pads/wax. I never buy new.
here are my previous new board weights no fins no wax. (with tailpad)
508 SP FST - 3.777
508 SP RF - 3.270
507 BP RF -3.000
602 SPit FST -3.173
606 alt FST 3.150