hey Alpha,
welcome to Automotive Forums.. while you might think an '88 is downgrading, an '88 to a 2014 Harley Sportster is very comparable to your Shadow (i've had both)..
the reason i started at 1988 is it is still a bump up to 1200cc, and VERY affordable; at $2500-5500 all day, possibly even with some custom mods..
but you could jump from 2014-2020 Sporty and still be under $10k if shopping wisely..
and you could always go 2021 Iron 883.. while only 54 c.i., it still packs a punch, has a very nice "buell"-ish look in O.D. green and flat black, is brand new, full warranty, zero maintenance, and under 9 grand with full options at most HD dealers..
and while it will probably come new with Michelin (and these are great shoes), i usually swap out after the third oil change to Metzeler; as regardless, of whether on my Shadow, Magnum, or mini-hog, i just love the side grab at 45-55+ in 3rd or 4th when you deepen the throttle..