RE: Which choice
At95 kg.,the GO 185 will give you the volume and width you need to be able to uphaul easily.
It has lot's of room for "progress" as you can put larger rigs on it and have a really nice large floaty shortboard that goes prerry well in light winds (down to about 10 knots for a fellow your size with a 9.5 m2 rig.
The reason your older BIC 6.4 m2 rig is so heavy is the fiberglass mast.
These masts were inexpensive, but heavy.
Modern masts weigh about half as much as the blue green BIC 460 cm mast from the 80's.
So, get a modern high carbon 460 cm mast and and modern lightweight aluminum boom (or carbon if you can afford it) and your rig will be much easier to uphaul.
Put this rig on the GO 185 and with it's wide, stable design you will be sailing around in no time.
Hope this helps,
P.S. Also, get some lessons on larger boards like the Start if they are available in your area. This will cut weeks or months off your learning curve.