Hi SBC i'd be surprised if a tabou would let you down. they are great shapes.
i tend to agree with the other guys about volume. now excluding old school narrow shapes and sticking with modern wider shapes typically your volumes work out around the folowing.
lightwind board is your body weight plus 20-25 and that gives you the litres. so for you at 65kg an 85-90lt board will float you and get you home and a 95lt board would just make that more certain and be uphaulable with practice.
your high wind board is your body weight plus zero or your body weight minus 5
so around 60-65lt
your nuclear board is your body weight minus 20 so 50lt for you. i guess that's a kids board.

although stepping down from a 125lt board to a 95lt board will feel a bit shakey at first. it is the thing to aim for and once you get used to it and start using it in 12knots and up you probably will only use your big board on really light days.
my 125lt board (my weight +20) gets used from 5 knots to 25 knots. at 20 knots i can easily sail a 95lt (my weight -10) and use it up to 35-40 knots. if the wind dies though it's a struggle to get home.
edit** p.s. if the 105 is a really good deal then just do it!.

they're great boards and there is only about 3cm difference in width. the main difference looking at the tabou site is the tail width. the 95 is narrower so it will stick better in the higher winds.