Iím right around 80 kilos and use the Futura 93 with 4.5 to 6.5 sails. You just need a smaller fin for the smaller sail.
The 133 should work great with a 6.5 freeride sail and freeride fin around 40-42 cm. I ran my 133 with a 38 cm fin and it was a little too small. A Drake 48 cm Drive fin worked great with the 6.6 but Iím going to pick up a 42 for stronger days with the 6.6. If you can squeeze a 9.0 on your 490 mast then I would. My biggest sail for the 133 is 8.5 and Iím about 9 kilos less then you.