Follow up post:
Completed the SS! Mounted the Superbe Tech RD on her and got everything else done. Test ride on my standard 3.7 mile loop was cut short as I added another 16 or so miles via a ride to the next neighborhood up north. Initial impressions were GOOD. I really like this bike.
Things to do: re-toe the brake shoes (very loud and much vibrating of the brakes under medium pressure after being fine), fiddle with the Superbe Pro shifters more than just tightening them mid-ride, swap out the ST RD eventually.
Good things list: My few years of refining my fit setup to frames paid off with this. I sit very neutrally on this frame when coasting and suffer no ill fitting when braking or pedaling (body weight shift). Really, I gotta hand it to Schwinn on this. The bike's handling is such that it nicely asks you to guide it along--no assumptions of wanting to steer more slowly or quickly than your inputs. And "OMG" on the in-the-drops while out-of-the-saddle high speed sprints--the way it winds up and sprints along with you feels phenomenal.
Also, the hidden spring Superbe Pro brakes with their paired levers have an extremely light and smooth feel--I couldn't ask for better. It was what I was going for and I got it!
Compared to my '85 Peloton, the wheelbase of the SS is a whopping 7/8" (22mm) shorter (39 3/8" or 1.0m vs 40.25"). 1984 Schwinn Peloton & SS had a 73.5°/74° HT/ST and a 39.0" WB (23" frame). 1985 Peloton and SS had a 73°/74° HT/ST and a 39.5" WB (23" frame). So I see where the length differed. I will say that my '84 Trek also had a 73.5° HT and I really thought that was a great angle in terms of stability and response.
I understand modern bar/brake hood (level) fitment/setup. I understand indexed shifting. I like both things a lot. I am now considering how much I really need either as, between this and my Supreme that recently 'showed me the light', I am having an absolute ball with this most-tactile riding experience, and it's comfortable!
Enough feels, here's a picture of her (there will be better ones...):
