There is a thread here: https://www.rx7club.com/forum/showth...19551&posted=1 That deals with making the OMP on a series four accept two stroke oil and bypass the engine oil. Whether it's worth doing is up to you.

I added a post to it today that talks about gravity feed vs *is the pump a pump?*. Some pictures but they're hard to relate to unless you have taken a OMP apart.