To add to Jim's good advice, the flex discs can be pretty much "stuck" in place and have to be pried loose.

BTW, you don't have to put alignment marks on the two crankshaft halves, they are already marked there are two "knots" on one piece that match one "knot" on the other piece. Marking the position of the flanges on each end is a good idea and maybe that's what you were talking about.

Good luck,