While I have two mid 70s Peugeots, I would base any decision on just a few factors:

1. Since they are two significantly different sizes, which one fits? I can't see both of them fitting the same person. Not sure which is correct, the frame sizes or the standover. Hard to believe 2 cm in frame size = 1 1/2 inches in standover, as there are 2 1/2 cms in an inch. Pictures look like there is more than 2cm difference in frame size. Size/fit is a deal breaker.

2. Does either bike have the usual upgrades: in particular, aluminum rims and cotterless aluminum crankset?

3. Rust? Pull the seat post, look down the inside of the seat tube for the dreaded rust. Depending on what you see, that would be the clincher to me.

As far as components, the Simplex unit on the UO8 is really bottom end, I kind of like Suntour.

All that being said, I like my 1975 UO8, and with alloy upgrades, it is a pretty light bike for that era (I moved "up" from a Schwinn Continental to the UO8 in 1975 when my 1972 Continental was stolen).

The price for either bike sounds reasonable, assuming bikes are in ready to ride condition.

Enjoy either one!!