To answer your question only bore out the needed dimension, .020 will not affect reliability at all. The most ID FEEL safe at would be .080" over. Wiseco pistons are the standard in this industry and hot rods cranks are also a good piece. May want to check out andy at m&m's cranks, they will be what i go for next after my hotrods gives out (which hopefully wont be for a lonnnnnnnnnnnnngggggggggggggggg time)
Cody