You could use an up-to-date version of core and apply (not copy / paste) the changes to the new version.
This would be the preferred way.

I'd suggest to never use outdated software (especially not a 3+ year old software). Particularly if it is a software which directly handles value (BTC in this case).


Also, you are referring to the guide as 'the guide'. Can you give us a link so we can take a look at it ?