Well done both. Sounds like you've engaged his interest. I hope he'll want to share playing it in due course! Cleaning won't take long.
Lapping doc on its way by e-mail.
If you can get it all cleaned up before you go away, if your Northumbrian holiday takes you anywhere near Hexham, you may be able to solve the problem of getting four odd size pads of the right sizes by visiting
Arthur Haswell - I can't vouch he'll carry the right stock, mind (you need clarinet pads!), so best to phone in advance. Otherwise you'll have to find a helpful local woodwind tech (most will carry extensive/relevant stock, but may not be all that understanding about non-modern, standard instruments) or mail order from
Windcraft (click that link, then
Clarinet, then
Pads - Premium Deluxe Leather) - or, as you're only an hour or so from them, visit them in Maidenhead. You'll also need some shellac or a stick of sealing wax. The problem with mail ordering is getting the right size - measuring the key-cups isn't that accurate a guide! You may also need to adapt the pads if they're too deep, in which case spares to allow for ruining one or two may be needed.
The pads you need are the leather covered clarinet ones - use the Premium quality. Flute pads, whilst more suitable in some cases regarding thickness (i.e. they are thinner than the clarinet pads) are all "skin" covered - Goldbeater's Skin as used on Bohm flute pads - and they aren't really suitable on wooden flutes, especially if the tone-hole edges are at all sharp. They'll work, but won't last. The ideal would be leather covered felt on card, 2mm thick, but no-one seems to make such commercially at present.
I'm afraid you can't just go on the outer diameter of the key cups for choosing your pad sizes. 1mm less then that should be close, but you can't count on it. I advise you to buy enough pads at the size you think you'll need from measuring and then as many again the next size smaller (minus 0.5mm - the pads come in 1/2mm steps). Even then, you may find some aren't right. Buy at least one extra in each size too. Problem is, the antique key cups just aren't that regular (not perfectly round, inner hollow not concentric with outside shape.....), and because they were mostly cast, the depth of the cup can be very variable and uneven - you may well need to thin pads as described on
Terry McGee's website (or I think I've written about how to do it on C&F) or even grind out some more of the metal (it is usually quite thick). Very often the 3mm thick pads just won't do as they are and you have to adapt them, especially for the very short keys where tone-hole clearance can be an issue - the G# and short F especially.
The wind tech sources won't be much help with the stopper cork. For that you'll just have to trim and file/sand down a piece of good quality wine cork - not a terribly easy job! Large size hole punches like
these are helpful if you can borrow one just a little wider in diameter than the bore of the head (probably not worth investing!). You need a finished cork about 2cm long which fits snugly (airtight but not jammed fast) into the head bore and has a flat, smooth, straight-cut down-tube surface. Grease it well before test insertion when you get it near size and when it is ready to use. If you like you can seal the down-tube surface with superglue and sand that smooth. We'll deal with positioning it when you reach that stage.