Overlaying Map QGIS 3 (oblique secant cylindrical projection)

I am trying to overlay a heightmap of Canada (EPSG:3857) with an old map scan I have (https://geoscan.nrcan.gc.ca/starweb/geoscan/servlet.starweb?path=geoscan/fulle.web&search1=R=294063).

The projection of the scan I have come to find is an oblique secant cylindrical projection, and I am hoping to reproject the heightmap to this projection so everything aligns properly.

I was wondering how I would go about doing this with QGIS3? I have looked into using the Georeferencer Add-on, or using gdalwarp but I think I am confused as to what an oblique secant cylindrical projection is and how to define it. I have tested a few of the cylindrical projections in QGIS but nothing seemed to align properly.