I haven't really looked at your mod nor do I know how you did it, but just moving SH3 files over to SH4 doesn't guarantee it works. As you may know, SH4 has been upgraded and improved with new controllers and behavior of old controllers is not guaranteed to work 100% the same as in SH3. So yea, I think you may have to run through the files and compare them with a SH4 sub to see what the fundamental changes are, and try to implement them as such...
Keep it up and keep digging, I'm sure you'll find it
