i dont know if i would trust just pouring diesel into the cylinders to free it up & then running it... (although i have used trans fluid with a little acetone to free up a few old dirt bike motors that sat for years & they worked fine afterwards)
thing is when they sit,,, the crank seals dry up... so you're probably better off just tearing the motor apart cuz its most likely going to need seals anyways... theyre cheap & its good to know it has fresh seals in it
you dont really want to hone chrome bore cylinders,,, its thin & you'll burn thru it if you hone too much... fine steel wool will clean up light rust...
kawi oil pumps dont fail much... you can always test it & im sure you'd be able to find one if its bad..
if it were me,,, i would try to free it up with trans fluid/acetone.. if you can get it to move,,, flip it over & let it sit for a day to drain out & then do a compression test before splitting the case to do the seals... if it builds good even compression,, you could get away with changing the seals without pulling the top end apart
pull the exhaust off & look thru the ports to see how rusty the cyls are