Lack of paint inside the bass drum is right for the times. As is the chalk 20 scrawled on it. Makes you wonder who would work at the factory if they couldn't tell just by glancing...after working there some time.
Mufflers look ok to me at first glance. The dual bass spur system may well be original. I'd have to do some serious desk research. Hopefully somebody else will know.
VAT and shipping will be expensive. I'm not sure if you have specific customs duty as well. I presume you will have VAT.
It is possible to ship in one box by nesting shells, but only if the hardware comes off the drums. Nesting can be done if somebody knows what they are doing, but is dangerous in the hands of wannabe wrappers. I'm not sure what the current limits are but there was a time when you could get away with shipping USPS (US postal service) and they were about half the cost of other courier companies. But they keep changing the limits on package size. You need to be very accurate with that or the cost may bite you by doubling. And thanks to volumetric pricing (as well as weight -- whichever costs you the most!) you need to be fully away of your shipping options.
Those of us who have to pay for international shipping learn the ropes or our wallet is quickly emptied. Our USA brethren don't always understand about the effect that has on pricing of vintage USA gear in the rest of the globe.
Judging by the feedback this is a good seller who knows his vintage gear. That's a good sign.
Good luck with it. Looks lovely.