I recommend short, with curved tip. If you use a strait feeler gauge you have to bend it to get correct angle with bucket and lobe or youre going in at an angle and the measurement wont be accurate as it feels tighter than it really is. I just made this mistake and had it pointed out to me. Whether you get a good set or whatever check feeler gauges with a micrometer. If you want the calculation to figure out correct shim youll need for the adjustment you’re shooting for i have it. And if you order k&l shims they run as follows, for instance 2.60mm shim is 2.68mm 2.50mm is 2.58mm and so on.