Well as we know that if you REALLY TOUR that fuel is the ultimate equalizer.. Many builds would never make it one day in this heat and at time's 89 or worse 87 octane fuel.. I was in Ok and all we could get was 87 ... stock bikes in the group where pinging..

So for the best touring engine I feel that you need to be able to run 87 fuel ( which by the way I know tune just about everything on now. Its not about peak numbers but thats another topic.
keep a long skirt and short rod , better ring pack than maybe a few others , its going to be about riding it anywhere if you really tour.. And by that I mean tour not running the super slab.. sure fuel can be better there but get off the main hwy and get on some of the old two lanes and enjoy the trip means that fuel is going to be hit or miss..
So if what ever you build can be de tuned to run on crap fuel then your fine in that area and that is going to based on the comp ratio..
I am going to re tune my 124 on 87 as well and then compare the numbers to 89 and then 93.. In the past it's not much of a gain maybe 2-3 on avg . but it will have a much less aggressive timing table . But what ever works for that combo is all that matters