How to get more low-end power, Sachs 504 (1 reply)

I've pretty much completed converting my Westlake's 504/1b to 504/1a configuration. Mods to date include 12 mm square bing, opening up the exhaust port in the cylinder, and adding the larger-diameter exhaust header. It's still got the stock 50 tooth rear sprocket.

I'm more interested in improving the low end than the top. Can this be improved by altering the ignition timing? If so, which way; advance or retard?