That bearing is showing pretty much normal wear for a high-mileage engine. There are four layers of material on an insert bearing- - - -steel backing, a layer of copper, then a layer of soft metal similar to Babbit, and a top "flash" layer of pure tin less than 1/2 thousandth thick for quick wear-in to minor irregularities in the crankshaft surface. The bearing in the picture is worn to the copper- - - -one layer away from the steel backing that will do major crankshaft damage.
I'd suggest pulling the crankshaft out and have a competent machinist measure it for out-of-round and diameter differences from one end of the journals to the other (taper wear). If either dimension exceeds acceptable wear limits, it's time for a regrind or a crankshaft replacement. The machinist can also check the main bearing bores in the block for out of round problems, particularly the bore with the welded cap.
Jerry
