You seem a bit disappointed at the lukewarm response to your plans Colin, but I suspect that is because it is a bit hard to discern what the plan is... Wanting to bolt an engine that does not exist, (and does not seem likely to ever exist) is a problem too...
I have not built or flown a Q, but have read a bit about them. The QAC newsletters claim the LS-1 predates the Roncz, but I hadn't previously heard the claim that the Roncz was based on the LS-1, and don't see what advantage would be had substituting one for the other. They were developed to stop the GU pitching down in rain, and it is claimed the LS-1 works. The plans are out there to build the LS-1, why change it?
Check out quickiebuilders.org for a lot of information, and more Quickie builders and flyers than you will get here. You don't have to LEAVE though, a lot of what is chewed over here will be relevant. You will also find a link to an Aussie builder who supplies cf spars for the LS-1.
I think most builders stop when they do the sums and realise they will have to go way over the designed max gross weight if they want to do something radical like carry a passenger AND fuel. Most of those advertised for sale have low hours, maybe for the same reason.
I understand the UK (assuming this is where you are from) regulator is just as restrictive as the Australians used to be. The rules here used to mean you could only build to plans, with no deviations other than the ones THEY imposed... Are you able to make the changes you want to?