I'm familiar with the figure (one of my all-time favourite halfling sculpts - and no ruddy cookware on her head!), but as to how it scales with modern 15/18mm I really couldn't say. I've compared her to a 15mm Polly Oliver ACW figure and she's clearly of chunkier build. Against an Essex ECW musketeer from the mid-90s she's clearly bigger.
The modern stuff? 'Twill take a wiser soul than I.