Congrats on finding a sandcast! Looks like you have a bike that is mostly there. As I see it:
The Good
Correct frame and engine numbers (Its a sandcast!!)
Appears to be nice paint on the tank (hopefully it is a correct wrinkle tank)
Double-cut front fender
18 inch rear rim (often changed for smaller rims). Hopefully a rolled rim.
Correct carbs (often changed for later easier-to-adjust carbs)
The front brake appears correct with the longer rib on the center of the back plate.
The Not-so-Good
K1 airbox and seat
Incorrect paint on the fork ears
Missing the left controls
Missing the side covers
Incorrect grips
Missing the foot peg rubber
Missing the passenger pegs
The Unknown
I suspect that those are HM300 exhaust pipes, but I can't be sure. They appear to be in decent shape, but no-number exhaust pipes are correct for your bike. If the exhausts have no stamped numbers on them, then they are original.
The rear fender appears correct from what I can see, but it is possible that it is a three-hole fender from a K1. Look under the rear fender to see if there are three welded nuts to hold the rear brake light or (the correct) two.
The instruments appear correct, but could also be from a K1. Check to make sure the red line is at 8.5k to be correct.
The tank should be a 17 liter wrinkle tank. Open the filler cap and you should see wrinkles in the metal.
I'm sure others will chime in. And thanks for offering it to the sandcast community first!