Egge Machine deals in older engines. Searching 413ci they have stuff.
Offenhauser sells a lot of older stuff still... https://offenhauser.co/
Doing a quick search, it seems places like Speedway (so likely Summit as well) sell parts that fit the various engines in the 413 family: https://www.speedwaymotors.com/shop/413-chrysler-big-block-v8~131584-180-7
This site gives a good overview of the RB engine family: https://www.allpar.com/mopar/383.html
Like Pepperalls said, Summit Racing, Speedway Motors, and a whole list of others sell the goods for your 413 from stock to performance. Edelbrock makes performance cylinder heads as well as Trick Flow if you're looking for more umph. Here is also a resource for casting dates, etc.: https://www.enginelabs.com/engine-tech/a-guide-to-mopar-v8-cylinder-head-and-block-casting-numbers/
A lot of RB stuff will interchange so if you see, for instance, a cam grind that is for a 440 and wonder if it will work in your 413, it will. As do intakes as long as you don't have Max Wedge heads. Also, the shaft mounted rockers make doing valvetrain work a LOT easier than on my Ford small blocks I currently have, or the sb Chevy engines I used to own. I can do valve seals, or valve spring replacements on a Chrysler engine in about 1/3 the time it would take me on anything else.
Also, if you're restoring your Chrysler, Send an email to Galen Govier, or check out his site. He has about the most complete listing for Classic Mopar cars as far as options, decoding, numbers produced, the whole nine yards.
Another good resource would be Richard Ehrenberg, the tech. editor for Mopar Action magazine. Very knowledgeable guy when it comes to restoring, resto modding, or simply repairing Mopars. He's a very good resource.
I know some having done some work on Mopars over the years, but those guys leave me in the dust with their knowledge, so check them BOTH out.