Henwood, if everything goes well, you will make your connection, but even then, not by much. Your arrival from Europe is a busy time at JFK, and it is possible to lose a good 30 minutes just in taxi delays and ramp congestion. After claiming your luggage and taking it through Customs, you will give it back to DL employees for your onward connection. The SLC flight will almost certainly be leaving from T2 and you will be clearing immigration and customs at terminal 3. So once you clear security with your hand luggage, you will likely have about a 10 minute walk to the SLC flight.

Again, there is a reason that 105 minutes is the minimum connection time at JFK.