That sounds about right, as the seal rope will have a tendency to spread out to the front and rear as the bolts are tightened. I've also found that it helps to turn the crankshaft back and forth a little as the main bearing cap is tightened. If I recall correctly, there is about a 1/16" gap between the seal area of the crankshaft and the block, and also the main bearing cap, so the seal does not need to compress all the way to the metal.
Jerry
