Dougie, using the VP150 to make two DIY M2 replicas doesn't seem very practical. M2 crossovers and a tube of the right length and diameter for bass tuning, besides suitable enclosures, would be needed. Actually, Tom's suggestion about getting a second VP150(if available at a good price)to use as a vertical pair of main speakers has merit. Turning horizontal centers vertical, at least as an experiment, is something that I've suggested several times. Alan reported excellent results a few years ago when he tested vertical VP150 as mains and thought they could possibly be sold as such.
You can experiment now with the one vertical VP150 connected as a single mono main speaker(disconnect the regular mains, set the receiver to mono and all the other speakers except the sub to "none"). You don't test stereo imaging that way, of course, but it gives you a general idea of how the speaker sounds in that orientation, by flipping it back and forth between the two.