Peter - done
Fiona.
OK, the ones in the G# and F keys look pretty OK, and maybe the one in the Eb key. the one in the Bb key certainly looks too big/fat. You said you have some a half mm smaller? What do those look like? Provided they'll cover the tone-hole properly, I'd say the next smaller pad would definitely be best in the Bb key. One thing you will find is that, when you fit them in with shellac/sealing wax, they do kind-of set/squash further in than you expect with a dry fitting, especially when you "float" them and press the key cup down on them in their beds.
Bear in mind the old pads have been squashed for donkey's years! I'd be inclined to try the G# and F for real and see how they go.
Melt a drop of your sealing wax into the key cup - you won't need much. if you move fast you may get the pad onto it while still liquid, but if not, hold the key with pliers and warm the back of the cup (with drop of was in it) up with a spirit lamp (if you have one) or a fag-lighter. Then place the pad onto the molten wax/shellac. Just get it fairly squarely set, but don't worry too much.
Now mount the key on the flute body and, holding the key open (with a cloth or glove to protect your fingers) use your flame to heat the cup again - do it at an angle which lets the heat rise past the flute as much as possible to avoid scorching the wood, though it won't scorch too easily - and obviously try not to burn the edges of the pad. When the pad rises because the wax/shellac has melted. close the key and press it down. (This is called "floating the pads in".) Check the pad is centred over the tone-hole and not catching the edges of the key-bed etc. The adhesive will set pretty fast, but you can reheat and adjust more-or-less as much as necessary. Having a blunt probe (table knife blade, manicure gadgets....) of some kind to push the pad around while adjusting it is handy. When you have done all 4 keys and visually checked their action and rise, try a suck test on the body to see if they're sealing OK. If you can post photos of them both resting closed and held open, I can advise again about any action adjustment or any reported problems.