The 7.3L is an amazing motor in terms of reliability. It can be modified to produce tremendous power. The weak link on that truck is the transmission.
If you look at the 2002 F350's tow rating, it's likely in the 9-12k range, so you're not gaining any additional tow capacity, but you may be gaining cargo (pin weight) capacity:
https://www.fleet.ford.com/resources...s/2002_All.pdf
The Ford will have:
1) Better low end torque, but not as much overall power.
2) Worse brakes
3) Better pin weight capacity
4) About the same total tow capacity
5) A 4-speed transmission, versus the 6? speed in your Chevy.
The big issue for me would be the brakes and the 4-speed transmission. I wouldn't tow that trailer with a 2002 7.3L Ford.
Newer diesels (although expensive) have come a long way and can now tow up to 31-32k properly equipped... I think you'll need to look for something a little newer.