My coat is based on McCall's pattern M4864

Changes I made were to totally recut each pattern piece along the bottom adding ten inches to the back and side pieces and making a smooth curve from the edge of the front piece down to the back pieces. I ignored the sleeve caps and the peplum (waistbandish pieces)

I made cuffs using a different pattern for an Argyle jacket although they are a very simple shape and easy to make. I also pinned the darts together before cutting the jacket out as I didn't want darts interrupting the tartan pattern on the front of the jacket.

One thing I did was to fuse lightweight interfacing to each piece so that they didn't skew out of shape as woven fabric is stretchy on the bias.

You could PM me for more details if you want.

back on topic... I think lightweight wool in a different sett size as long as the colours match is a very good idea,.