The best would be to shop the original Porsche workshop manuals and the spare parts books. Now it is a bit complicatet as you need the spare parts book for 356B T5 body, then the upgrade to T6 body and the 356 C supplement. On workshopmanual you can work with 356B manual however some topics are shown at the 356 A manual and are not repeatet in the 356 B manual.
The 356A manual is a big book ( phonebook ) and the 356B/C manuals come in several binders.
Here in germany every Porsche dealer will sell you all the pre 1983 workshop manuals & parts books.
In the staates you will find them at the usuall parts supplieres and on ebay
I know very little about restoring the 356 model line and the reason is that I have never read much on the subject. If would check the Porsche Club of America web-site. The PCA technical spokesman for the 356 is Dave Seeland and if anyone can help its david.
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I live in Germany and would like to know where to find some manuals. I am restoring a 1965 356C and need to get a hold of a wiring diagram and some other diagrams. If you know of any Porsche dealers in the Baden-Wurttenburg/Hessen area that would sell a manual I would be very interested.