Alrighty then.... 33-34 degrees total is a reasonable safe starting point for those particular aluminum heads at 10.4:1 in "our neck of the woods" on 93 octane, but the motor might "like" more. If you want to really nail it, the best way is to take a day/night and your tools including timing light and go to the track (you need an accurate set of e.t. clocks). Start there, make a pass or three to get a base line, then bump it up a degree and make another pass or two. Make sure as best you can that all the conditions are the same for each one (same engine temp, same starting line procedures, etc.) - repeatable consistency on each run is more important for this than trying to lay down the absolute 'best' time. Chances are as you add timing, you'll start seeing better e.t.'s. Then you'll reach a point where the car either doesn't improve or maybe even falls back a little. The previous setting then is the optimum for your combination.
I'm running round port 72cc E-heads on mine at 10.0:1, and 36 degrees total seems to be what it likes. The DUI HEI I'm running has 20 degrees "in" it so that means my initial is at 16 degrees. The car starts and runs fine, doesn't overheat, etc.