I would set the initial with the vacuum gauge method or to 15-18 would get you close then shorten the slots to get 35 total (initial+slots) & the $22 FBO plate is the fastest/easiest/cheapest way to accomplish this then toss the one heavy spring with the elongated loop on one end & sub in a mr gasket 925B or MP light spring in its place for a start keeping the OE light spring. any combo of one or two springs will let the weights advance in a linear rate. here's a chart tho the crane kit is no longer available there are chebby and hardware store springs that can be subbed in. always keep the OE light spring. you want to be close to the pinging point but never over it. you also do not want the advance to start any less (point X) than 100-200 RPM above the hot in gear idle speed which is what you will see at the stoplight. EDIT (1) mr gasket 925B spring will give you full advance at ~1200 RPM and both of em at ~2400 RPM