Personally, I'd be more focused on the trap speed than the et. MPH is a better indicator of proper tune than et because of fewer variables like traction etc. I'd tune it for the best mph then tweak the chassis and tire pressure for better et.....jmo,

Johnny

Well if the dominator is handy, slap that sum bitch on there and see what she'll do.

I think your pretty close to where you wanna be on the timing @ (40) most SBC's race motors I've ever tuned/ran like around 38-40.
34-36 sounds slow, every combo is different though, yours may be the exception, I run 41 in my BBC.

Cp

i just put on a quick fuel 850 on my 388 sbc 13.1 solid roller in a 3100lb car and went from running 7.05 to 6.80 running 36 total timing and 82 sq.jets. i was running a 750 holley.i would play with jetting and timing on your combo.