Here are a couple threads that I remember from when I was new here. There are others that did rebuilds, but James and Alex have the best documentation from what I remember. Neither is going to serve as spoon-fed instructions, but there are many good points and some comments from the Porsche engine expert Jake Raby.
http://986forum.com/forums/diy-project-guides/54170-my-diy-engine-rebuild.html
http://986forum.com/forums/diy-project-guides/49562-engine-removal-rebuild-re-installaion.html
You will need to explore further, but I think that in both cases, they had engine difficulties later and have been gone from the forum for a few years.
You can also find many good comments from
BYprodriver. He went through Jake's training and did some nice upgrading. Where the other two were figuring a lot out as they went, Bill knew what he was getting into from the start. Search his posts on your own, but save this spreadsheet in case the internet loses it:
https://docs.google.com/spreadsheets/d/1roke7O_Yyigm8AaE1Gei1ncGhFN6sh9sgAE9H0gh9Ks/edit#gid=0
I have two engines in my garage that are too far gone to rebuild, but have been good to pull parts from - two other engines I have are going back into cars. I would caveat JFP's advice that the extent and definition of a rebuild should be factored with what you are starting with. Taking a low mile engine and doing full maintenance such as chain ramps, cam adjusters, IMS bearing and bolt-ons can be [much more] affordable. The correct Porsche tools are very expensive, but there are alternatives. Check here for blemish/bargains:
https://www.ebay.com/usr/type4store?_pgn=1 Some of the alternative tools [and procedures] can ruin your rebuild. Personally I do not see the practicality of a full DIY rebuild vs buying unless you want to do it for the exercise and enjoyment.