The best wheel to get is the 15x7 Cookie Cutters as those are the lightest but you can always go for a set of early 15x7 Phone Dials first and then find a set of Cookies later. The offset you will need is 23.3mm and the size is 15x7.
There are a few guys selling some non-running 944's with 15x7 and 15x8 Fuchs for around $600-$900 range. Too bad we can't use those wheels for racing.
You can also check with Parts Heaven in Hayward and see if they are willing to trade you 2 sets of Cookies for your 16" Fuchs. Like I said, I sold my 16" Fuchs for $1,000 and the Cookies should not be more than $300 for a set so do the math and don't end up on the short end of the stick.