v8 ENGINE INTERCHANGE DATA NEEDED; what fits what?

[Z432]

96 XR7 with 4.6ltr V8 Romeo auto.

The only thing I have found that would count as an interchage guide is:
http://www.babcox.com/editorial/ar/eb40228.htm

My understanding is from this page is that I can fit a 96, 97, or 98 Romeo with no big problems. I know that places I have called only say 96 fits 96, but I understand that to be because of some sensors or something like that, is that true?
I have found other newer engines, but I don't know if they will fit. I know where I can get a 99 Interceptor engine for $500.

Thank you