James, I agree with everything that
@Amy POPContent said except points 3 and 4. Doing 3 and 4 is essentially editing your work for a robot, don't do it unless you really can do it naturally.
I think you should definitely publish these on your own blog, spend some time promoting them and
measure the response.
If you did give / sell / place them on other sites, you might get a short term gain ... but great content compounds over time, so it's best on your site. I imagine that in your industry (of which a cousin of mine is in also), there aren't many practitioners writing about the work ... so there's an opportunity.
Your blog is the engine in long-term, sustainable online growth - so take time to build it well.
As you publish content there, you can see how it performs - which articles get the most engagement, get the most shares and
drive the most leads - then do more of what works, and less of what doesn't.
This will all help you to understand the content that your potential customers are seaching for, giving you greater insight to be able to pitch the bigger profile sites in your industry to write pieces for them ... this will help you to build your own profile a bit.
Most of these sites allow contributors to include a link or two back to other online resources - if it is helpful for their readers. Thus you could include a link back to your site.
Other thoughts:
1) find questions on Quora which fit with articles you've written, answer them and link back to the relevant article (quora com/topic/Stone-Masonry - just add the ' . ')
2) in order to fulfil point 1 in Amy's comment, ask your customers to tell you what they want to know (or wanted to know before buying from you) about stone masonry ... your content needs to reflect their challenges / questions / doubts .... etc
There's my 2 pence worth,
Alistair