If you want you can send it my way for testing. I am in America, and yes you will need NTSC. I bought a DVD set for my wife last year from the UK, and one of the two DVD’s were accidently sent in PAL format. I could see the image and hear the sound, but it looked like the verticle hold setting on the TV was going ape. I recieved an NTSC version a few weeks later and all was resolved.
The problem in conversion is that PAL runs at (correct me if I am wrong) 25fps and NTSC is 29.97fps. There might be a slight difference in frame rate resulting in a slightly “slow motion” look, but this is only an educated guess. I have never personally done a conversion between the two. The screen resolution is also slightly different (NTSC being slightly larger) so there might be a bit of a “black line” around the screen like in viewing a wide screen movie. Nothing to noticable though.
If you would like send the DVD my way and I’ll test it out for you. PM me and I’ll send you my physical mailing address.