ISO: yeast conversion for old elams bread rec. whole wheat+rye+molasses

i have old (?35-40 years?) elams flour recipe, cut from the flour box, for a great heavy bread, calling for 2 cakes compressed yeast, + whole wheat flour + whole rye flour + molasses, used to make it all the time. i wonder if it has been brought up to date, with dry yeast, maybe other changes. i learned to cut back on amts. of the above flours by 1 C., and substitute white flour, or it takes forever to rise. i'd like to avoid hunting up the compressed yeast it calls for. thanks, pcr