Yeah, elbow grease will save the day when other methods are lacking.

A guy in the UK in the 60's posted an article in the Model Engineer about a small table top Horizontal borer he made, using just raw castings and no machinery.

Using the traditional old time methods of chipping the casting with a hammer and chisel to get beneath the skin then filing and scraping etc.

This was purely to prove that anyone can make a machine without a mill or lathe using the methods and hand skills already proved, even though time consuming.

In a build like you are doing, I think the linear ways will give you more joy, but that's just my preference.

I was quite tickled by the gluing of the column pads, and at least you have access to a surface plate to check your build, so all is not lost due to inaccuracy of alignment.
Ian.