Roy,
On gearing, I have fitted a 21T crank sprocket in place of the original 25T on my Dyna. That reduces its theoretical top speed from 140mph to 118, in other words to about 19mph per 1,000rpm. The only other mods are a jet kit (it has a carb), SE air filter and SuperTrapp mufflers. Roll on in top gear is now like a Harley should ride and gear-changing is significantly reduced. However that is contrary to the mis-guided popular belief that Harleys should lug monstrously tall gearing, hence never get going!
I don't know what the performance figures of my Dyna are, but I have had the S&S 107 in my Glide dynoed. Between around 2,700 to 5,500 it gives 90 to just over 100 ft lbs of torque. With top gearing of around 24mph per 1,000rpm, fast touring on the Continent, just a couple of weeks ago, involved travelling at between 3-4k rpm, in the sweet spot of that plateau of torque. Is that what you are after?!
Returning to your bike, if you have
raised your gearing, without substantially increasing torque to compensate, I question the benefits. I have over 100bhp to back up my 24mph per 1,000rpm! I suggest around 4k rpm at 90mph for a sensible top gear for Continental cruising, unless you have similar bhp and torque figures to my S&S.
So one suggestion is that you get your bike dynoed in its present form, to see what you currently have. The scope to build upon that is substantial, whatever the numbers! In the extreme you can bore and/or stroke your motor, raise compression, gas-flow the heads, plus all the other things we have already mentioned.
A few years ago I had my original evo motor stroked and tuned by a reputable builder (now retired unfortunately) and it ran as sweet as a nut. The more you research this topic on the internet and seek advice from us rank amateurs, the more, not fewer, answers you will get! At present you are onto a hiding for nothing.
It sounds as if you have serious ambitions for your bike, as I had when stroking mine and recently installing my S&S. There is in my view only one worthwhile solution, namely find yourself a reputable engine builder, discuss your requirements in detail and evaluate if he understands and can supply what you want. Don't presume to tell him what to fit or how to achieve the results you want, that is for him to judge - that is the reason for going there. Then get him to build it for you! You cannot achieve comparable results yourself without substantial experience and expertise. If he is worth his salt, he should make it all seem very easy and you will marvel at the final result, believe me!