I came from Wisconsin where all the Germans settled. I played in bands that performed laendler's, reinlander's and schottische's. These tunes were typically played by polka bnads.

Unless there is another version of this form of music, which there may be, you will want the schottische's to sound like the ones on the link I am including.

We commonly played Oh Susanna Schottische. They have a very distinctive form. The phrases are 2 regular measures followed by a strong 1,2,3 where the dancers would hop, hop, hop. haha

You can especially hear this in the Norweigan Schottische on this page.

I would find out the clients ancestory. My guess is if they are from Germany or northern Europe, they will want what is on the link I have included.

As far as I know, there is nothing Scottish about a schottishe. And if there is, I suppose it came over when the Nord's invaded what is now the UK.
http://www.polkaconnection.com/The-Best-of-Louie-Bashell-P7607C715.aspx

The other name for Oh Susanna Schottische is Noch Ein Immer Trepchen

Hope this helps to allow you to have the kind of music your client is really expecting to hear.

Best
Scott