No, your overall length won't tell you much, if anything about where your shoulder is. You need specific shoulder gauges to measure shoulder setback like the Stoney point/hornady comparator with head & shoulders gauges or the sinclair tool. You can also do it relatively well by feel just start long and slowly screw your die down untill the cartridge gets hard to chamber and then becomes easy to chamber again. As you FL resize without bumping the shoulder the shoulder will move forward, making it harder to chamber. Then as you screw the die down more the die will start to bump the shoulder back untill chambering is easy again. Just go real slow and only screw the die down in 1/8th turn increments. Then leave your die set.
I use a gauge attached to my calipers that measure from the datum point for the cartridge. It basically measures from a point on the shoulder. If you measure the overall length, sometimes resizing will actually INCREASE your length, since the brass has to move somewhere. Here is the gage I use.
