The biggest problem you're going to have is heat related. While lots of folks install radios into DIN slots and get by with it, it is not an ideal location. This is especially true if you run a high power rig.
As for size, there are dozens of different radios which will fit. Just choose one that fits your needs.
If you do a good install, you want have any interference problems.
I do have some information on my web site you might want to read.