I am having brake issue on my 1970 duster

I agree we need more information. I am wondering if you have disc or drums? If you replaced the shoes, they will need to be adjusted out which can be done through the hole in the backing plate, the automatic adjusters will fine tune them if you do a series of forward and backward stops.

With regard to bleeding, I agree with the post from @harrisonm as to how to do it. I would only add what someone else said regarding the need to first bench bleed the new MC and then when you do bleed, do the furthest brake first (passenger rear, then passenger driver, then passenger front and finally driver front). Using a vacuum pump at the bleeder valve can work but air bubbles don't always seem to get "sucked" out in my experience. Or you get a leak on the hose to bleeder valve and it looks like it never bleeds cause of all the in-leakage.