I have a 69 C10 with a D-Max in it, and last year I went 10.67 @ 126 with a 1.49 60ft time with the stock trailing arms set-up and a set of coil overs. My truck dyno'ed 760hp and weighed 5100. I think with 700 hp at the wheels and a weight of 4100 you should run low 10's.
Here are a couple pictures of my firewall.