Help my key way shattered in the pulley and the crankshaft plus all the splines ground off both of them

Ever hear of a product called "Belzona"? It's used in the paper mills to repair shafts that got chewed up where bearings ride. Applies like epoxy but gets as hard as metal and can be machined on a lathe the same way. I used it many years ago to fix the rounded-off square on the end of a speedometer cable. It's still working fine. This stuff can be molded with a mold release agent, and the parts can be used to form the mold.

You can weld new metal onto the end of the crank too, but then how are you going to machine it in the car? The crank is cast iron, so you're going to have to preheat it a real long time and that will take out the seal.

Under such circumstances, on car repair is not going to work.

The recommendation by caradiodoc might work. You mentioned a lot of weld etc and it faisl. Primary reason is because the repair is not perfect.

The crankshaft runs under load of the various drive belts and your crankshaft has been worn out of round. The pulley has to turn perfectly round and your repairs most probably has the pulley turning eccentrically. This would result in a heavy load on the crank pulley bolt etc and they would give way in no time.

The other thing you need to replace would be the timing belt crank sprocket. The impac of the pulley would most probably have damaged it resulting in it not being level and when the pulleys is tightened, it is not at 90 degrees with the crankshaft.