The redline is generally a function of the valve train. Especially the lifters and springs. If you want to raise the rpm limit, you'll need to change those two items. And, really, unless you're racing, there's not much point in it. Except that it sounds cool.
When the distributer and cam gear go, it sends all that trash through the engine. The
oil filter should pick it all out, if there's not too much. When that happened to me, I pulled the pan and cleaned it out, and disassembled the
oil pump for cleaning and polishing. Then I flushed it by doing a couple of
oil changes with cheap oil and a good filter. I ran it that way for another year without any problems.