First EVER run
I think you can get a little more out of it with a slightly looser converter and maybe some headers, but thats a respectable time, no matter what anyone says. Its quick, but not blazing. Good numbers for the 318 and setup. Do you have the stock pistons? The time may be a little slower than it could be if you are running big valve 360 heads with the stock rotating assembly.
That will lower the compression even furthur and throw away valuable low end torque, which doesn't help your 60 ft time.
My 318 with stock bottom end and heads, Comp .440 lift cam, 4 bbl, manifold, 2.5" Flowmaster exhaust runs mid to high 15's with 2.76 gears in my Duster, so your time is in range, but it could be better. You could get down into the low 15's easy, depending on setup.
-Justin