I’m sorry I missed your question for so long!! You certainly can blend the two, making some adjustments as you go. One difference between the two is that guided reading groups are usually based on the kids who read the same level while the strategy groups in CAFE are based on the need for work on specific strategies at any level.
However, you can start out with your leveled groups is that is where your comfort level is. You just need to be aware of the strategies that each child within that group needs.
For example, you may have a group reading at a level at DRA 12 or F& P Level G. Within that group, however, you may have two kids that need vocabulary support, one that needs comprehension help and one that only needs to work on fluency. So, you may read the same book with your group, but when you start your individual conferences, you will need to ensure that your are addressing their specific needs.
Another difference you might notice is the time for group work. Many GR programs suggest a 25-30 min time. However, brain research and the newest studies have shown that students’ attention and ability to listen start to wane in a much shorter time frame. Shortening your group time will allow you to confer individually with students as well.
I hope these suggestions may help. Please continue to ask questions, and we’ll make sure you get speedier responses ;).

I was at a conference in Chicago for the Daily 5 and CAFE. The “Sisters” discussed the brain research of Ken Wesson regarding this issue. Good luck!