for what it's worth i use a whole lot less cam than that 308 and idle about 25 degrees before TDC. my initial is 18 with one light primary spring that bumps the timing up and idle speed in neutral is 850rpm. this works very well for me. you're doing over 40 degrees of overlap at .050"; i do about 18. trying to make that work with 10 degrees initial would be a big challenge. like said, fix the ignition first and the carb will be easier to manage.