Upgrade old SSD with OSX El Capitan installed to Mojave

Hi,

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I currently have an Mac Pro 2009 without an Metal compatible GPU. I therefore cannot upgrade to Mojave etc. I am going to build a Hackintosh with an Z370M board and Intel i7-8700T (ES version which is 1.60GHz).

I have two questions:

1. Can I use my old SSD with everything installed after the Hackintosh process is complete, or do I have to upgrade that to Mojave? And, if that is needed, when I install Mojave on the SSD, while not booting from that SSD, wil it erase the rest of the disk or just update the OS and leave the rest intact?
2. Can I overclock the [ES@1.60GHz](mailto:ES@1.60GHz) to the retail clock speed of 2.40GHz?

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Regards, Patrick