I can see your route, and it is not the cheapest circuit of Europe. It would help if you told us what things you would like to see. the mountain climb is fine.
I ride an Enfield and plan my routes to suit it. Still from time to time it is simpler to use the faster roads and motorways for certain sections. Unlike many here I don't find the lack of a high cruising speed to be a problem. I do try to avoid peages (tolls) but that is 50/50 driven by economy and my preference for riding at a relaxed pace. My own bike likes running between 50-60 mph. It is a 500cc Electra with standard gearing.
I generally dislike cities (although Colditz was very pleasant) so try to stay away from them although not adverse to using ring roads, Camping , particularly wild camping is in France very easy. Although not strictly legal in some other countries. Cities are often expensive, but many French and Belgian cities have cheap council run campsites. For instance there is a really good one in Mons (Belgium) right in the city centre.
One thing that bothers me is that if you are used to the characteristic of a 350 Enfield, perhaps the performance of a modern 1200cc superbike may come as a shock. Add that to the controls on the wrong side, Driving on the wrong side and the different nature of European driving and you suddenly have a lot to learn. If you could work a route using less motorways and maybe a few less city centres it may be better to have a lower powered bike which would be considerably cheaper to run.
As an aside, I used to ride an 800 cc BMW it was faster than my Enfield, but the odd thing is, on longer trips I tend to do more miles per day on the Enfield than I did on the BMW. Not having to stop so often for fuel is one reason, the Enfield does double the MPG of the BMW, so is halves the cost of travelling. Two days steering clear of peages (toll roads) will pay for one night in a hotel/BnB/motel.
Hope this helps.