Your over-rich condition is chrome plated. Use that tiny air cleaner for a skeet target and get one that will flow enough air for the engine to use the fuel it's getting. That thing is doing the same as running with the choke pulled out about halfway.
There's supposed to be a spring and a plastic thrust button in the hole for the grease fitting or grease cup that holds the distributor shaft snug against the housing. That will eliminate most of the shaft wobble that's messing with your timing. I modify distributors to use a Torrington needle bearing just under the centrifugal advance that eliminates all the wobble at the points. It's a simple machining procedure, and it's a lot less expensive than paying for a HEI distributor.
Unless you can figure out a way to flow more mixture through the ridiculously restrictive cylinder head ports, nothing you do to "improve" the intake or exhaust will make much difference. Dual exhausts are nice to look at, and with a set of free-flowing mufflers you'll have every neighbor in a 2-block radius looking for ammo for his shotgun, but noise is not power. Have fun!
Jerry
