As others have stated, your combo is a little mismatched.
First place to pick up some power is in those heads. The trickflows are my go to, but the stock 516 heads are also right up there.
A thinner head gasket will also help, The Mopar performance steel shim head gasket #P4286754 is a 4.38" bore, 0.020" thick (about 5cc volume) that could be used to up the compression a bit.
I would definitely get a set of rear gears, 3:55 for all around driving maybe even some 3:91’s if you like.
Or just put on a 150 shot of nitrous and go with that..