Sorry to bump the thread, but I think I finally found Spiro Agnew's position on abortion: He signed a liberalized abortion bill as governor of Maryland.
https://www.washingtonpost.com/archive/local/1996/09/19/nixon-vice-president-spiro-t-agnew-dies/6616ed01-311a-4b13-8051-dd0ce3782552/?utm_term=.6496e1d66634Also, candidate Alf Landon disliked Reagan bringing up abortion in politics, so it's clear he was pro choice.
http://articles.latimes.com/1987-09-07/news/mn-4187_1_great-dayI tried to find information on John Bricker's position, since he lived until the '80s, but I couldn't find any.