To be honest, I would not put a dime in the stock heads with their small valves and restrictive ports. See if you can locate a set of 452 casting heads, as these will already have the improved runner shape of the '67-up heads (915, 906, 452 castings, among others) and come with a more generous valve size plus hardened seats. The problem will be losing some compression due to the open chamber of the later heads ('67 915 heads have the better exhaust runner and closed chamber, but are pretty hard to find these days).
I agree with brainsboy to upgrade to electronic ignition, though I would not waste my money on a MSD setup for the engine your outlining. A stock Mopar electronic setup will be more than adequate.
The bent pushrod scares me a little, I think I would definitely pull and inspect the cam.
The stock 383 Magnum from 68-up was rated for 335hp. With all the same parts and modifications, a 383 will make the same hp as a 440, though it will require about 15% more RPM.