Some 360 magnum questions

So, I finally fired up my 360 magnum, set the timing, took it for a short test drive ('67 dart 2 door hardtop). I have a few questions and and an issue (the thing I dread most, an oil leak). It runs cool, no issue there, great response, kickdown is working perfectly (A904), very smooth and gobs of power.

First, I set the timing according to spec, 32 degrees mechanical advance at 2800 rpm, 50 total with vacuum. It runs fantastic, but I did notice when it's warmed up it was starting a bit more slowly, i.e. cranking a bit slow as an engine does when the timing is too far advanced. I don't hear any detonation or anything, the AFR is 14.5 at idle and cruise, but lower under throttle, like 12.5-13. It wasn't overheated or anything, at least the coolant temp was 200 degrees. I'm just wondering if the hot slow cranking is indicative of the timing being too far advanced. Should I retard the timing a bit, thoughts on that? It's a Mopar Performance distributor and I'm using FiTech 30003 TBI four barrel.

Second, when I start it cold, the oil pressure is 50-60 psi, but after it warms up it goes down to a bit less than 20 psi at idle and just under 40 psi at highway speeds (2800 rpm). That seems a bit low to me, but tell me if it's normal.

Third, ugh, I stopped to check everything after a few miles and the rear main seal is leaking oil. OMG, I HATE rear seal leaks. I've had many engines not leak a drop, even junk yard pulls, and only a few with rear seal leaks. Are 360 magnums more prone than not, or did my builder just not do a good job.....ugh, I dread the thought of having to pull it after all that work. Anyway, if there are super triple lip seals or any special advice there, let me know as I'm pretty sure I'll be pulling it out and redoing that rear seal in a short time.

Thanks all.

Brian

P.S. the 360 magnum is a BEAST! My TTi shorty headers/2.5" dual exhaust is a bit loud, I'm gonna have to modify it to tone it down a bit, but man does that engine have power.