Hi Alex, no need for any measuring. If you look on the back of the Hardy reels the size will be stamped on them. I can not see the Perfect well enough, bit fuzzy, but it looks quite modern and very clean. Might put it somewhere safe to keep it looking good.
The others look well used which is normal.
I would use any of the others. When people say don't use they mean don't if it's totally unmarked-mint. Hey, these reels were made to use and so what if there is some paint loss, those reels will work perfectly for many many years to come.
I have a Perfect and a Princess, one is mint and the other close to it. I thought about wrapping them in cotton wool but only one life and they will still be around when I am not so I use them. Only thing is be careful when fishing where you lay them down to change a fly or unhook a fish-put em on grass-not gravel.
Alex use them and enjoy them.
Looks to me your gramp started with a Rimfly like many of us did and worked his way up to the Perfect. The Marquis shows he delved in a little salmon fishing and the Abu would probably have been his salmon spinning reel. Nice bit of history there

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Good luck-Chris.