All you need to do is take stuff off the bike. Mainly.
2 models in 80.
A mag wheel model, 80SG, with disk brake rear. Seat clip clip locks to frame
A spoke wheel model, 80G/SII, with drum brake rear. Seat hinges to the frame
Getting the bike running properly electrically, connections/earths and the charging system checked. Spend the money on the charging system straight away is better. It is then reliable.
Both run a fat 16" rear wheel. Removing the battery box and air box opens up the middle of the frame.
Removing the battery means you need to completely change the charging system with a PMA, this will run into money. Converting the bike into kick only.
Alternatively replace the factory sized battery with a smaller sized, ( dimensions), battery with the same cranking amps. Will need to make a tray under the seat, (do a search plenty of threads on this, may b a link in tech menu), for electrics and a battery that lays on its side.
That is the main. The rest can b changed after the bike is running and as money becomes available.
Removing the front guard removes the factory bracing. Need to buy a fork brace of some kind of cut the front guard down front and back. The bracing is in the arch over the fixing points. You will see what I mean when looking at the guard.
Seats from Texavina are popular and reasonable price, some have had small fitment issues. Again it depends on what model you get as to the amount of fabrication needed. Clip on seat, 80SG, frame will need fab work to fit a bench style seat. Hinged, 80G/SII, frame they sell a seat where all that is needed is to swap the hinges.
Local seat maker is Wess from counterbalance cycles.
https://counterbalancecycles.com/
He has a good rep, may b a little more expensive but his seats can be custom made to b more comfortable than Texavina.
Exhausts, can b used and again changed when money becomes available if the look isn't what you want.
Back to the charging system. If it isn't charging it usually means the rotor is caput,
(recommended to get a rewind even if the rotor is working, 45years old and will break down soon),
there is a guy on here who does rewinds at a very reasonable price
https://www.xs650.com/threads/rewound-alternator-rotor.54276/
(Jim writes a very good description on how the factory system works),
and there is a cheap way to upgrade the reg and rectifier by replacing them with an automotive regulator and bridge rectifier. Some small fab needed + a wiring pig tail. This is 100's of $'s cheaper than a PMA making the bkie an every day reliable ride.
https://www.xs650.com/threads/diy-reg-rec-5twins-and-jim.55842/
The rest depends on how much you want to spend. Can b done cheap with the look you basically want. Still work and change things to get the finished look as money becomes available.
A link to models, differences between models and some other links,
NOTE; read tutorials, (
post #7), and information
https://www.xs650.com/threads/xs650...-other-information-including-xs750-850.30569/
One last thing. If buying a mag wheel model , 78SE, 79SF, 80SG and changing it to spoke wheels requires a bit of work.
NOTE; Expensive sourcing a set of spoke wheels in good Nick or made up, new spokes good rims
There is a link to what's needed in, post #7, in the above link. Swing Arm can b retained, brackets need to b removed and one added, brake parts from a spoke wheel model to b sourced, some parts can b bought aftermarket. Again all in the link, post#7.
NOTE), 81SH model has mag wheels. A one year only where the mag wheel has a drum brake rear. A spoke rear wheel, (and front, any model from 74-83 interchanges without any modification).