You don't have near enough gear. Also, I've never seen a good set of headers for early A body cars. Ever. If they are not custom built, they are junk and I don't care whose name is on the box.
Did you degree that cam?? Or dot to dot it? That's where I'd look after I dropped a 4.30 gear in it. If you can't or won't do that, change the cam.
My second guess is you'll be lucky to be at 9:1 as I'd bet you didn't degree the cam and didn't actually measure the compression ratio. I'm not talking about doing a bunch of math you found in catalogs and online. You need to pour the heads and do a downfill on the Pistons and THEN do the math. Otherwise, you are just guessing.
You didn't say what plug you have, but pictures would be nice. What about the fuel pump you are using?
Also, I've never ever seen any cam make 1/10 of its HP under the sweet spot so just ignore that post.
If you have answers for the above, it should run 11's. Provided you can get it to hook and your clutch doesn't break the drivetrain to pieces and how well you can actually drive a stick. It's essentially a lost art.