Help with sweet bread recipe

I'm getting ready to make Wihlfahrt's Basic Sweet Bread recipe, formula 55 
in the FAQ.

It's for about 25 pounds of dough, which is a bit much, even for me.

I've taken 20% of the ingredients and my calculations look correct, except

for the yeast.

He calls for 1 pound of yeast, which I assume is baker's yeast.  I took
0.4 
of that, and got 6.4 ounces.  Taking 20% of 6.4 ounces I got 1 1/4 ounces,

which is 5 packets.  could this be correct?  The rest of the stuff adds up

to 88 ounces plus 3 eggs, a pinch of mace and gratings of half a lemon.  
The flour is 45 ounces, so 1% would be 1/2 ounce.  One and one quarter 
ounces would be almost 3%.

Since I have so little experience with enriched doughs I'm at sea here.

Anyone have any thoughts?

Barry