That’s quite a big step from V4R3 to V5R4.
You should have no problem with migrating your data, you should be able to save all your database files on the V4R3 system and restore them on the V5R4 system without any problems.
I suspect that your applications will also migrate without any problems, however these will be converted to the new version when you restore. If you get any problems with the conversion (make sure you check all your joblogs thoroughly), you may need to re-compile some of your programs.
Hope this helps.