I am in charge of a 150th anniversary celebration of a church cookbook that includes several "light biscuit" and "roll" recipes using a yeast starter. The recipe for starter given in the cookbook involves hops (difficult for me to find). I'm wondering if I could use the mother starter (barm)  from Peter Reinhart's BBA that I keep on hand in place of the "yeast" called for in the two recipes below:

"Light Biscuit"

1 quart warm milk

3/4 c lard and butter mixed

3/4 c yeast

2 T sugar

1 t salt

flour to make a soft dough

The dough sits overnight and is then rolled, cut, and risen again before baking.

"Rolls"

Pint scalded and cooled milk

1/2 c yeast or 1/3 cake compressed yeast (Anyone have an idea how many ounces a 19th century yeast cake had?)

1 T sugar

a little salt

butter the size of an egg

1 quart flour

The dough "stands until light" and then is kneaded with additional flour (for half an hour!). It rises again, is rolled, cut into rounds that are folded into halves (sounds a bit like Parker House rolls).

Many thanks for any advice!