Is there a performance distributor for slants and timing settings

Hi is anyone using a performance/ racing distributor in their slant 6, and where did you get it.

I have a performance built slant and am using the stock distributor and timing advance from pre-resto. I am wondering if there are some recommendations to get the most power.

It has 10.5 compression, ported head, Comp solid lifter cam, sorry I don't have the cam specs with me. Breathing thru a Holley 390 4-barrel and offenhauser intake, and hooker super comp headers.

Right now I am using 110 octane ($11.50 per gallon ouch) and have the timing at 5* BTDC, with a MSD 6AL box. I would like to get the octane lower to save cash, but get the most power without detonating.

Whats your guys experience on this.. Thanks