(1) set the initial with the "vac gauge method" then (2) buy/use the $25 FBO plate to limit the total (initial+slots) to the "std" for your eng (35-sb) which will get somewhat "close" then (3) mix/match springs so you are just under the pinging point at WOT up thru the gears on your hottest/driest(most likely to ping) day then (4) plug in the can to ported & adj it so you are just under the pinging point in everyday driving under varying RPM/load conditions & adj it (slope not the total) with the hex wrench. Peoples' hearing varies & there is "silent" ping so give it a cushion. "manifold" porting for the can is touted by many people & locked out timing has its place. Bottom line: NO pinging, you want to get "somewhat" close that line but never over it. Any combo of springs (except for the OE heavy spring with the elongated loop) advance in a linear rate so any combo of chebby or transdapt or mr gasket or MP springs are OK to get your ideal combo.