My engine is a different combination than yours, dont go by me, go by your sparkplugs...I run 30 intial then i am at 18 with everything on. Now i check my plugs and they sometimes had a little black spec on some, i prob could have pulled more timing and dropped some fuel out of it, BUT i was in that process and the car was picking up....I dont know what head your using, what type of quench etc...whatever you do, start out conservative all you can do by pulling too much timing is slow the car dow, add it back in 1-2 degrees at a time thats all...watch the plugs and the mph on your time slips...Best thing is contact Monte smith on here, he can sell you a flow tool and tech you how to use it properly as well as put you in the right direction as far as jetting , fuel psi, timing etc.