Tom,
The 2100 carb was common to engines in the Ford line. so it came on 390 engines as well as 289's and 302's. The 390 version is a lot different, but looks the same and will bolt on. But it will get far worse gas mileage and may be way to rich.
If you give me the complete number on the front left lower corner that is stamped into the throttle plate area, I can tell you what engine it came off from.
Curious as to why you wish to replace you current one? I rebuild these all the time for people.
Rob