That depends a bit on what chassis/chassis plate you have. The V1 chassis plate, tower and shocks combine to a situation where the droop is limited by the chassis, not the shocks. As such, a 4mm lower tower may be used on it without limiters/spacers or a shorter shock shaft (after all, the chassis is preventing your arm from going down lower.
If the chassis does not limit the droop of your car for any reason (mods, aftermarket parts etc), put limiters in your shocks until the ground clearance at without load/weight on it is about 40mm on the rear (which is approximately the droop level of the 210V2). Some very high bite tracks may require you to go down to 37-38mm to prevent occasional grip rolling, but for me the 40mm has worked well in most circumstances so far
PS: As you might have heard me mention, you don't necessarily need shorter shock shafts. Spacers with a 3.5-4mm hole diameter work fine - I 3D print my own, but you can buy them or even make them from the ball stud/suspension spacers that you got in the kit, just drill/ream out the hole until it fits over the shock shaft without friction. With the spacers you can fine tune to the millimeter, instead of the 3mm difference the shock shafts offer.