I have been struggling with a similar issue with mine. What kind of distributor are you running? I bought a new MSD set-up and installed it straight out of the box. I wasn't getting full centrifugal advance on the timing until almost 3800 RPM. $%@%^ Barn Door Springs!!!
You should be able to soften the springs and get full advance timing at a lower RPM. The difference should be significant. Mine just seemed a little lazy on the bottom and the further out I went the harder it pulled. I would check into it...