the motor's a basic bbc 4.35" bore x 4" stroke deal, aluminum heads, 228 - 238 @ 0.050 marine cam. i'm i going to be stuck with running good pump gas?
how much timing am i going to beable to get away with? i'd like to be in the 33-34 degree range total.

if i have to run good gas i might as well order bigger chamber heads and the M-1 procharger....

thanks

The aluminum heads buy you some compression, standard marine 89 will probably work.

I am sitting at 9:5 and timing set at 36 BTDC. I always run 91 and would not think of running anything else. I can not afford to have a meltdown

You'll probably be ok -especially with Aluminum heads.
It also depends on the shape of the combustion chamber/piston configuration. Good circulation/swirl = 89 will be fine.

Yes, a small chamber with a large quench pad and close piston-head clearance will also allow higher compression on pump gas.

the heads would be the Edelbrock 110cc chamber ovals for the 9.5 to one build.

What ignition are your running?
Most of the new stuff has knock protection.
If you don't go wild on the total advance, you should be good with 89.

My ZZ502/502 has/had 9.6:1 with aluminum heads and GM recommended 92.

89 octane will be fine with the 34 timing as long as your fuel curve is good and you run at 140 - 150 deg
Don't be surprised if you make more power on 87 with less timing though.

right now stock, but i'm going to get MSD stuff for it when the motor goes in.