Just the sump
I have one of these in the Glasair I just finished. You could change the engine to an updraft or forward induction simply by changing the oil pan. Either would make the build more straightforward since there are many examples of both types already flying. That said, if you were willing to do a good bit of fiberglass work to modify the cowl you could end up with a truly unique and beautiful airplane. The Glasair Super II uses a large NACA scoop on the side of the cowl to feed the rear induction. If you did this you could eliminate the existing RV8 chin scoop altogether. Since the NACA is entirely internal there would be no protrusions from the cowl. It would be quite sleek.
What you seek to do is a great deal of extra work and will add considerable time to your build. You might consider selling the oil pan to get one with a more conventional arrangement for the RV8. The IO-360 B1E is used mostly on Piper Arrows and the aforementioned Glasair II. If you decide to proceed with your engine I can give you drawings and specifications for the NACA.