The sprokets are marked 'Inlet' & 'Exhaust' and are located on the cam shafts not just free to spin. If you have the OE camshafts, you can lock them in position by locating 2 spanners on the flats on the cam shafts at the chain end. You will have to have them crossing eachother at diagonals. Then you use a pair of mole grips to hold the 2 spanners together which in turn stops the cams shafts moving.
As you've mentioned already, use cable ties to keep the chain in the correct position until everything is tensioned. Make sure you use ALL the new bits that you have in the kit as some of the bolts are stretch bolts and once they have been used once you MUST throw them away.
;-)
