That is a good saying at the end of your post.

Engines do not "know" what kind of pumps are being used. There is really no reason for calling the oscillating pump a four-stroke pump, other than the fact that four-stroke crankcase pressure, pressure that is needed to drive the VP-30, is not normally considered to exist with the four-stroke engine. Paul McIntosh proved the latter theory wrong as he pointed out a few years ago in the rec.models.rc.air newsgroup. Paul used a Y-connection to obtain pulse pressure for his four-stroke engine's Perry VP-30 pump.

Yes, you can start an inverted two-stroke if you are willing to learn the drill. My Top Flite Nobler (RIP) and its inverted two-stroke engine took me a while to learn so that it started quickly. That was long, long ago. Most folks just aren't that patient these days. I know the learning curve was steep for me (1966). This was before electric starters and such were popular.

Ed Cregger