RE: F-type 158 + Gaastra GTX 10.5, planning?
Last season I've had the F-type 158 and used it with a 10,6 V8.
I could plane from about 5 m/s and I was 103 kilo.
With your weight there shouldn't be a problem!
Some pumping may be required and if that doesn't help enough, you might consider a light wind FW fin.