best would be an A/F ratio bung welded into an ex pipe for an LM1 or 2 or wallace racing has some good plug reading pics. for the power circuit I would run a vac gauge into the interior so you can see what # you have at any flat spots & to just get a baseline on your numbers at different driving conditions. EDIT with the stock cam you might be pretty close on main metering, not sure if the 1413 is jetted rich out of the box but likely it is. then pick the right springs by working with your vac gauge reading numbers. MORE EDIT for a stumble confirm that the AP tip in is immediate & of enough duration & that float level is correct then richen rods/jets as needed.