72 360 first start question

will it stay running with a steady throttle above idle? yes reversing/going halfway is correct to find/confirm TDC with carefull measureing. I'd set it at 15, line up the magnet, see if the rotor is fairly close to the cap terminal & give that a shot but the more I think the more I think vac leak but we might get lucky. do ya feel lucky, well do ya!