You will have a difficult time hearing engine ping with that exhaust leak.
I mentioned a vacuum leak earlier in this link. I think that needs to be corrected before advancing your time and turn your dist. If I were you, I'd turn everything back, get that paint off the h.balancer and correct the vacuum leak. Then work the timing as explained above.
Of course, none of this matters with the exhaust leak. I think you said that you have a 360 in there. I have a pair of exhaust manifolds off my 360. Otherwise, get a pair of those 1970 AAR exhaust manifolds ($300 on average). If you think that converting your exhaust pipes back to except manifolds will be too much of a pain, then just find a USED pair of Dougs or TTI. Paying for new ones would be a waste of money for your application.
Party on!