Canidate number one: Carbolite 103 was the frame material used in the lower-end puegeots, later replaced with "HLE" tubing, and replacing "tube special allegre peugeot". Probably a bit on the weighty side. I have one like frame, an earlier UO10, and it performs well as a beater, but is a bit stiff as a frame.
Canidate number two: The worry here might be the seatpost. On some lower-end seventies models, Peugeot used a 24.4 seatpost, which is impossible to find replacements for short of scavenging.
Canidate number three: The best of the bunch. I am, however, unfamiliar with triathalon bikes. I'd ask about their ride characteristics somewhere else, like the triathalon board, because I frankly have no clue. And knowing ebay, it may not be a triathalon bike at all; the seller may have just stuck that in there to try and attract more bidders.
The other problem may be french threading. One and three may be late enough to dodge this problem (i.e. the threading may be English, both bikes are post 1980); however, the only time this is a real problem is in the bottom bracket (you can finagle your way around a french headset). If I were you, I'd consider expanding your search; Trek frames from the early eighties, for example, can often be found cheap and make fine rides; plus they avoid the standard French problems by being English threaded. Some Japanese bikes are terrifically undervalued as well. You might also spend a touch more; I watched a really nice PY10 go for about $175 a while back.
The agressive head tube angle you want may be a problem as well; most French bikes appear to have pretty relaxed angles to my eye, with exceptions spotted around (the 1973 PX10e comes to mind).
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