I'm pretty new to this so its possible I'm approaching this completely the wrong way. I have some drawings of plastic enclosures from different manufacturers, which I have been modifying to show exactly where I need holes and cutouts made. But then I got this one drawing that somehow seemed "huge". It was laid out in millimeters on a sheet over a meter long, where all my other drawings were in inches, and never laid out on anything bigger than an 11 x 17" page. I thought for a moment I'd ignore this, as all the dimensions shown in the drawing were already displaying in both millimeters, and inches in (parenthesis). But when I tried to add a new dimension of my own, the text (showing the measurement) was so tiny, again it made want to re-scale this drawing some.

Anyway, I've tried a few things to scale the whole drawing to seem like it was natively drawn in inches, and I'm about to throw in the towel. I first went to the Unit system and changed the Units Scale/Block units format to inches and applied that (yes I saved the original as is). Next, it now seemed to make sense why the drawing seemed huge, because now 1000mm page had become 1000 inches. So next I did a select all, and tried a scale operation, in which I just picked a point in the lower left and entered reference numbers.  I already had a length measurement in the original drawing that showed both 220mm  and 8.661 inches, so I just entered 220 for the first reference and 8.661 for the second.

After this, it seemed that all the drawn sections of this enclosure had now become proportioned as I needed! But that none of the dimension components of the dimensions representations scaled at all. They were all huge and bunched up over the parts the graphic entities. What a mess. I tried switching the dimension layer to the active one and attempted a similar rescale operation, but it did not yield the same success I had scaling the other entities.

So I'm posting because there must be a better way to accomplish what I'm trying to do, which is open a drawing and in one step convert all the whole drawing to a different scale and units.What I tried above would have been adequate had it not made a total mess of the dimensions, and would have scaled their visible components (arrows, numbers) to the same degree as I'd scaled the rest of the drawing. Any advise appreciated.