In high school I weighed 170, when I bought the XS650 I weighed 265. Now I weigh 170 and again. It's probably better to do push-aways and avail ones self of the dual pleasure of a classic mid weight better than a Bonneville scooter, and the freedom high school weight gives. Mind you, my ol' stock '83? XS got given away, built rebuilt swapped out and ended up as a street tracker, and then got given away back to me. I like her better now. If you wait too long the XS supply stream go kaputski... I'd live now. Man I wish I'd kept the stuff I've owned... Keep whatever you decide on.
A 883 sportster, with the carburetor, not FI, might suit better. Slightly less power, maybe 100 pounds heaver...
I like the brat style. I find myself wondering how this modification would compare from a handling perspective with the bike above provided by 40north. I guess I would expect the brat to have faster handling...
That's plunger rear suspension. Was common on bikes in the 40's as an improvement over rigid frame.
How a girder setup compares with a telescopic fork depends on the geometry - all the technicalities of rake, offset, trail. You can make a girder fork bike handle just as well as good teles, but if you're going custom you have the opportunity to configure the bike how you like it, from relaxed to twitchy.
But above all - good, tight, accurate handling will depend on how well the set up has been engineered on your bike.
Several fork designs can work well, like the Britten with a carbon fiber girder type, Bimota Tesi/ Yamaha GTS with hub center steering, BMW Telelever, and "a million" bikes with telescopic forks. But I would guess telescopic forks are more "manageable" for an amateur builder with limited resources, if good handling is more important than aesthetics