I have two sets of feeler gauges one of the blades on one set reads (.020 .508) and the other blade reads(.20) I know the manual states to set at .20 for intake and exhaust so I just want make sure I use the right one. The (.020 .508) blade is the thicker of the two and has a bend. The (.20) blade is quite thin.

 

I don't know the actual values, there is a range, but I'd go with the thicker of the two. Valves will lose clearance if anything, as the valves will wear into the seats if they wear, making the clearance less. I usually will set to the middle or a bit more on the valve shimming for that reason.