No. ALL H.O. motors were 50oz Ford switched balancing weights in the early 80's, 50oz was cheaper to do. Your casting number is from an '87 crank, so it's gonna be a 50oz job.
As far as the 28oz goes, all 351windsors were 28oz, and the early 302's were as well. There's some speculation out there as to when exactly the change occured, some say 1980, some say 1981. The things I know for sure, ALL 351w are 28oz, and all 5.0 (302 H.O.) were 50oz.
Hope this helps!
