First thing I would do is the things that dont cost like uncapping your exhaust it will help allot. Like bjuice was saying in his reply your mph is high for a 790 et sounds like its spinning out of the hole, so look into possible traction issues, play around with the air pressure on the rear tires, I would start low like 10 then go up till it starts spinning, you want to run as much as you can for the higher mph and stablitiy on the big end. Do a harder burn out or less of a burn out and see what makes the car hook better. Play around with your shift points too to see what helps and what doesnt . Also if your running a front sway bar take it off, it is of no use at the track and henders weight transfer. Next thing I would do is get a taller gear, it will help you out tremdously, I would personally go with a 488 or 513 if your not planning on doing any 1/4 runs the taller gear will get it moving quickly off the line, a small gain on the small time means a big gain on the big time. A higher stall converter will help a bunch too, my old camaro picked up a full half second when I went from a 10 inch 3000 to a 8 inch 5500.
Are you deep staging? deep staging will slow your et' by a couple of tenths. Personally I like the shallow stage technic, I roll into the first beam and then stall up some and inch in till I just barley turn the second light on, that way I know excactly where I am and I have a good running start at the sixty foot light. this wil help you be more consistent on the light and allot more consistent on your et's. Then you can adjust the way you react to the tree, then fine tune with adjusting air pressure in the front tires.( higher pressure helps cut better lights lowering it slows down your light ) Personally I run between 50 to 60 psi make adjustments accordingly at the track, but I wouldn't recomend going over 60psi.
The heads seem small for that big a motor too, you might want to consider getting some bigger heads or getting your intake seats cut out for a 2.25 vavles along with a bowl hog job to unshroud the bigger valves. Also higher compression and a solid roller would wake that thing up big time, basically where your at with your bbc, you are just scratching the surface, there is allot more potential there. Goodluck and keep us updated, Charles