Sacrilege - gearing up a fixed

Have you tried the wheel in frame, and fits ok ? Does the dish of the wheel place the rim in the centre ? and will the chain run on the smallest sprocket without rubbing on the inside of the chain stay ? If so don't need to worry

Very roughly

120mm rear spacing - max 5 speed block
126mm rear spacing - 6 or 7 speed block
130mm rear spacing 8 speed cassete upwards

hijacking the topic, it's perfectly fine to put a 5 speed block on an 130mm rear spacing? I'm building a bike up for my dad, and decided to have 1 chainring and 5 speed rear as he never change gear on the front.