Good morning, Jeff,
Your math is correct. But two points:
1) 145%?!?! Are you sure that's right? I've never heard of a starter
with over 100% water. Is there any chance that the author meant the
ratio of flour-to-water instead of the more typical water-to-flour?
2) You didn't tell us the third and fourth "ingredients"--amount of
initial culture you use inoculate the starter with and the time you
ferment the starter before using it. I'm not sure whether one needs
more than one feeding to achieve the conversion. But if very little
inoculation culture is used, then the starter's hydration will be
very close to the new target hydration after just the first feeding
even if the culture's hydration is different.
Allen
SHB
San Francisco