Even with a 4" crank with what you got and on pump gas, would get you low 11s.
Build a 360/408 short block on the side and enjoy the car in the mean time.
When the short block is done, put your existing top end on. Go run low 11's with what you have.
When time and $ allow, get some good heads 300cfm and stuff in a 256@050 .650 solid roller and go run mid 10s.
At this point the rest of your drivetrain will also need attention.