I assume you have looked on here first - http://www.thingiverse.com/search?sort=relevant&q=p3steel+v4&type=collections That doesn't give a lot though - but it does maybe show that there are no major differences. Maybe look up P3Steel V3 also. I would print and test as you go on each step - will it fit, does it fit, move on or find a part.
According to the RepRap wiki it's more of a frame change rather than a parts change. You could ask out to the author of the frame - https://twitter.com/alvaroreyrdz/ and see what they have on file for printer parts? If you get anywhere - remember to document the parts here for others?! :)