Looking up the part #'s at kawasaki-motors.com/ for the SR, and buykawasaki.com for the R, I saw that the head, piston, rings, cylinder, base gasket, and cases were different.
Here's the part #'s:
Part________
SR model_____
R model_____
prices for R parts
head_______11001-1301___11001-1291__$186
piston______13001-1290___13001-1295__$ 69
rings_______13008-1110___13008-1116__$ 33
cylinder_____11005-1585___11005-1569__$427
base gasket_11009-1817___11009-1994__$ 6
cases______14001-5264___14001-5262__$433
Looking up the SR parts costs at
www.bikebandit.com I saw that the head, cylinder, piston/rings, and cases were not available. So they'd have to be gotten from the UK (contact
corby.kawasaki@btinternet.com) although I have successfully used regular R model piston/rings, head gasket, and base gasket.