LD4B installation on a 75 318

So I've spent some time doing some carb tuning and checking the timing and then took it for a couple of test drives. It definitely has more "giddy-up" so I'm pleased with the results so far. I still need to figure a couple of things out though.

1) The thermostat housing is weeping a little so I'll need to remove it and try sealing it again.
2) I hear a vacuum leak but I haven't been able to figure out where it's coming from.
3) I've adjusted the carb (set idle speed and then adjusted the mixture screws) for maximum manifold vacuum. Manifold vacuum is 18 in-Hg with an idle speed of 725rpm in park and 580rpm in drive. My initial timing is 0 degrees.
At 1,500rpm my total timing (mechanical and vacuum advance) is 16 degrees with manifold vacuum of 22
At 2,000rpm my total timing is 27 degrees with manifold vacuum of 23
At 2,500rpm my total timing is 43 degrees with manifold vacuum of 23
At 3,000rpm my total timing is 44 degrees with manifold vacuum of 23

From all the reading I've done, 44 degrees is quite high. If I change my base timing to something BTDC (since all the reading I've done indicates I should be somewhere around 5 to 10 degrees BTDC), I should also adjust the vacuum advance pot so there's less vacuum advance? I'm running the stock distributor which must have a slower curve for the emissions equipment that used to be on the car so perhaps a new distributor would be a good idea too??