The latest version of AFKmud is written in C++, which means that if your old code is in C, anything that isn't a module, ie fairly self contained, will have to be modified to work with the base.
And even then, there's going to be stuff in that isolated module that still needs to be brought up to speed in order to work with the internal changes in AFKMud.
Aside from what Keberus has said...
I would create a diff against stock Smaug 1.4a, as that will isolate all of your code changes (I think)?
Then you can work your way through that diff, modifying the code as needed and adding it to AFKMud.
Not a perfect solution, but it's probably better than trying to search your code figuring out what is custom and what isn't...
To clarify here, diff your own code against stock 1.4a, don't try diffing against AFKMud because the resulting file will be larger than the codebase itself