I don't know what will actually fit, but as long as it does, it's best to go with a rim that's the same width or an inch wider than the tire you're using. Some have gone wider. But this allows more air pressure to be run while maintaining a full contact patch. The higher pressure also helps maintain a stiffer sidewall (longer life) and helps keep the car stable at speed. Many Stock class racers use 10" rims with their 9" slicks. Pressures range from low teens through the 20's (Lots of variables.) You'll need to experiment to find what your car likes.

Since you already have the rims, the offset may limit how wide you can go. Taller slicks with more gear will work better too.