The bars are a cosmetic issue and changing them will mean changing any and all cables and hoses. Brake Hose, clutch and brake cable. There is a lot of info about the quality of mikes XS parts and you will need to do some research or get advice on the parts you intend to replace.
You haven't stated, (hinted maybe), if you have bought the bike before delivery or are going to be able to have a look at it before actually paying for it.
Things i see you are going to have to do and things to look for to be able to ascertain if you are going to have to do certain things.
I see oil around the points lead going into the cam cover and it is all around the back of the engine and on the carb manifolds. This is a sure indication the cam seals will need to be done. Buy 2 sets because it is real easy to damage the seals on reinstall. Not just a novice problem either.
Weather you have bought the bike or looking at it before making a payment. Remove the side oil filter, (in the right hand engine case), and see if there are black pieces of hard plastic or other debris on the filter. If there is debris then the bottom screen filter is broken and will need to be repaired, (yes they can be), or replaced and depending on the debris, if it is black plastic then that is a sure sign the front Can chain guide is worn and will need replacing. The plastic d-laminates from the alloy guide over time so sometimes it is just a time thing, but if there is no indication this has happened then you may get a season or 2 out of it before having to replace the guide.
If you have to replace the Guide this requires the engine to be removal and the head removed. ................To back up a bit, a compression test should be done and if the compression is within 5 PSI between each cylinder then the bike can be run as low as 100 PSI but ideally anything above 120-130 will get you around for a season. 150 PSI is considered great for a standard XS650..................If the front cam chain guide needs replacing and you have low or lowish compression then it is an opportunity while the top end is apart, to refresh with a hone and new rings or a re-bore and new pistons. There is a cheap good quality alternative to Mikes XS Pistons and rings.
not trying to scare you but this is what you are up against.
The front brake lines will have to be replaced if you are going to remove the bars straight away. Mikes sells rubber or Stainless lines, if it is a matter of cost, the rubber is ok but will need to be replace in the next 3 or so years but Braided stainless will last for years. The cailpers and MC will need going through, dismantle and clean, or if it needs maybe some new seals and a flush. Ditto for rear brake.
Charging system needs to be checked for voltage output, Sometimes problems can be caused by faulty or corroded connections creating resistance making the charging system work harder and over heat, Bad batteries is also a major cause of failing charging systems. If it just a rotor they can be fixed/repaired/rewound, and with a cheap alternative Regulator and rectifier, (a lot of info on this), you can get years of service out of the original charging system
All wiring connections, bullet/couplings and earth connections, need to be taken apart, cleaned and connected again and the earth connections cleaned and contact points cleaned and all contaminants removed. This includes switches on the bars as well.
This is a start, electrical things i have mentioned are a necessity and the loom cleaning can be done in a day or 2 for a novice. this is something that has to be done for reliability sake. The best thing about this is you get to know your wiring.
Can't really see but it looks to have the cheap pod filters on the bike. Throw them away and get Pods or if you want go back to original filters.
Do the electrics before doing the carburetors, often problems blamed on the carbs can be traced back to faulty charging system problems.
Make a thread and ask questions before buying any parts because there are sellers out there who do make replacement parts that are cheaper and as good if not better than Mikes XS. On some parts Yamaha still supplies them and although they are more expensive than aftermarket, the parts quality is worth paying extra for.
Enough for the novel. Tech menu is your friend and keep to one thread then regular helpers will enjoy helping you on your journey