bolt pattern disc brake q

I don't know what kind of situations your missus is gonna get into, but
IMO
10" Drums should be more than adequate. You can always downshift on the long downhills.
Maybe splurge on an upgrade to the shoes and get the drums machined.Find a brake shop that can regrind those new shoes to fit the machined drums. Otherwise it's gonna take a long time before the brake performance will come around.
I had a 69 340 Barracuda with 10" drums all round. It had no problem slowing the car from 100 to 30.........multiple times.

Btw
I don't like Unilugs on the front. I don't like Unilugs at all, but especially not on the front. And I really,really don't like Pre-Owned Unilugs.
If you have your heart set on using them, make real sure that you have the correct length shank-nuts, and the correct AS-NEW washers.Clean both the mounting surfaces of all rust and dirt. Make sure the studs are in great shape
Torque them.
And check the torque every 100 miles, at least 3 or 4 or 5 or more times until you trust them to stay tight.
If your shank-nuts are too long, do not use common hardwarestore washers to adjust the length. They are too soft and will not hold the torque.
If that car is making daily trips thru the mountains, I highly recommend NOT to use Unilugs.