Templates vs Custom Builds: Seeking Advice for Client Projects

Hey guys, just looking for some experience/perspective with templates vs custom builds. I have a client that has basically designed of an existing webflow template. While these templates are great inspirations I have a few issues with them:

The class naming structure is confusing (not client first)
The style guides are typically very minimal
You piggyback of somebody else's work which leaves you at risk of
A lot of it is in px but I use rem measurements
I personally don't like clean up work, especially not if it's somebody else's work 😄
Not really compatible with the Relume workflow
... but you could potentially save you a tonne of time

Has anyone experience with using templates for client work? Any advise? I'm torn between "copying the template into a relume/client first workflow" and just buying it.