I think you are missing my point...
Firstly, I am not a proponent of the rocket or superized RVs, I dont even support fitting an O-360 into an RV-9. These may all work out for the builders and good luck to them. I prefer to stand behind the designer's recommendations. That is not to say I don't like the concept, but I listen to Vans and to my own engineering experience and gladly look on with interest.
Vans is a smart and shrewd businessman, he knows where to strike the nail.
Allow me to speculate....
May I suggest Vans would also be watching these rockets and superizing and be thinking this looks fun, they fit my company's design expertise and I could do it better and capture this segment of the market as well. If I (Vans that is) were to build a 260hp plus two seat aerobatic airplane what would be my approach?
The design brief for the engineering department would be for just such an airframe, then pick the best of the breed and the most popular configuration, fix as many of those pesky construction issues as possible and as best as we can make it easy and affordable to build ( just like the 12 ).
I think this is what the RV-14 is!
Like most I am a bit underwhelmed by the use of the IO-390, I certainly would not build one nor trade my RV-6 for an RV-14 with this engine, but I believe they see this as the entry level version. Lycoming seems to be appealing to the Experimental market to improve the acceptance of this engine, and Vans seems to suggest they are negotiating a good price such that the total package will be comparable to the RV-7.
So I'm speculating that the RV-14 design has been conceived to accept the bigger engine. The larger sizing and numbers seem to support this, none of the published data precludes this and it seems to simply make good sense to me that this is the approach.
If Vans never endorses fitting a big engine to this airframe - fine, I respect that and would not support fitting one - but then to me the RV-14 simply doesn't make sense.