I have got several NTSC Atari's in my collection in the UK.
Simplest thing is to find an NTSC compatable TV, I have an old Sony Trinitron CRT that does an excellent job. I also had a reaaly old 19" LCD non brand TV that did a brilliant job too. More modern LCD's seem to have more problems with the out of spec signal from the atari's
I am in the process of using the SCCC on my NTSC 400, not sure if I am going to convert it to PAL though.
In the past I have also had a hybrid machine with a PAL ANTIC in an NTSC 1200xl, so I could play the PAL only demos such as NEUMAN
Make sure that if you do buy one, that it is really well packed and they do not include the power brick. One that I bought had been wrapped in 3 sheets of newspaper and had the power brick loose in the box. It acted like a wrecking ball, what a sad way for an 800 to die.
As others have said , a 9v ac power supply is all that is needed, I think 2 amps minimum
Steve Tucker @atarimax is a great seller and I bought a couple of 1200xl's from him years ago, he may be a good place to start
Also, you may well be hit for import duty, so factor this in to any purchase, sometimes by the time you have paid shipping and duty it's not such a cheap option, it was great 10 years ago when the exchange rate was two to one, now the £ is worth jack schit
A sympathetic seller that may put a lower value on it may help