Heres my setup which is very similar to yours:
3450lb Dart(with me)
Magnum 360 with 9.5 compression, RHS indy heads, 228/232 .540 lift cam, 904 3500rpm stall, 3.91 gears,275/60/15 et radial tires. 85 octane gas. Ran a 13.8@98mph(1.91 60ft). Keep in mind this was at 5500ft above sea level and was 8400 DA that day, this would equal out to a high 12 second car at sea level. With your set up a larger carb would help out. I went from a 600cfm edelbrock to a 950DP holley and it went from 95mph to 98mph instantly without no tuning or changes on anything else. That change is about 25-30hp gain by a simple carb swap. My timing is set at 38* advanced. With a few changes to your combo you will be seeing low 14s high 13s