Without a dial-back light, just set the initial timing (at 900ish RPM) to about 14 degrees, then set the mixture screws to about 2.5 or 3 turns(or just set them properly if you know how) finally check the float level once more and once the fuel just comes out of the sight plugs, go back down a 1/4-1/2 a turn. Keep at it, my 383 with 8:1, 800 Double pumper and a MP 274 cam was running mid to high 13's and ran unreal.

Don.