This will (re-) kindle a long-running, er, 'discussion.' In theory, a bolt in tension is held in place by steel's elasticity and the bolt being stretched. Hence, 'torque-to-yield' bolts and lack of any sort of lockwasher on critical junctions like head studs. So, a properly torqued bolt in an application where there is no 'give' besides the bolt stretch lockwashers aren't needed, and may be detrimental. Either the factory or the DPO had put split lockwashers under the bolt heads on my front shocks, and the washers had dug into the soft metal of the shock body, pretty much making them useless as far as preventing the bolt from coming undone (facing these spots is a good idea, IMO, but don't take off too much metal). I still have the original shock bolts, which I believe are the British equivalent of our Grade 8.
The reasons for using Grade 8 flatwashers is a) plain steel flatwashers are relatively soft and will compress and relieve tension on the bolt and b) plain steel washers will deform and release tension on the shock. Since a Grade 8 is larger in diameter than the bolt head, you are effectively increasing the clamping force. For (a wildly approximate) example, if the area under the bolt head is one-half inch squared, the bolt tension is 500psi, then if your Grade 8 flatwasher is one inch squared, you are effectively putting 1000 pounds of force on each corner (the area factors cancel out, if you do the math). This reduces the shock's ability to 'wiggle and squirm' its way loose. The threadlocker is just insurance, but be sure to guesstimate its effect on the torque spec (less than oil, but greater than dry).
My experience is this does not quite apply to the rear shocks, which have unsecured nuts on the backside of the mounts. I tried the Grade 8 bolt/flatwasher/threadlocker-only approach, and a shock worked loose. I still use only a Grade 8 lockwasher under the bolt head, but I use a splitwasher under the nut. I think only using threadlocker on the nut side allowed the bolt to rotate and work loose; the split lockwasher prevents that.
I don't think safety-wiring is appropriate in this case. Safety wiring only prevents a bolt or nut from coming loose entirely, which is why it's widely used in aircraft where the results of things coming apart often ain't pretty. The safety wire itself is not strong enough to hold the torque on the bolt/nut, and there's still some give in the wire even when properly twisted (I believe the 'spec' is 9-12 twists/inch). Also, using safety wiring properly is almost a course in itself for aircraft mechanics--you always have to wire in the direction that keeps tightening tension on the bolt/nut, and the wire must be properly secured to an anchor, or another bolt/nut--and requires a jig to drill proper holes in the bolt heads and/or nut. One good thing: safety wire-twisting pliers used to be very expensive, but you can get decent ones at Harbor Freight at a fraction, and they work well enough.