Digging your build.
I have been following it for a bit.
If you don’t mind I have a few questions.
And a few suggestions…
Did you gusset the hard tail? If not run two “L”brackets on the top. It will also be a good mount set up for your seat.
I’ve never done a sportster but does the bottom bolt to the motor?
Because for some reason I was thinking the motor bolts to the backbone/seat post and front down tubes?
So, is the bottom of the frame just a bolt together?
If so I would run a rod/slug through it then weld it.
I have seen bolt together hard tails break and I’ve also seen bagger bolt together raked necks break and that would suck.
One other thing while your welding and cleaning things up, you should just weld a 1/4 inch thick by how ever wide “L” bracket to get rid of that bolt together rear brake lock to clean up that side of the frame.
I just eyeball it to make sure the caliper is centered and that there is enough room for the 90deg for the brake line.
Great work and can’t wait to see the finished bike.