We were using a set of the Dunwich pre-paints I bought from Doug a couple of years ago and the fitted in perfectly alongside Foundry, Copplestone, Hasslefree, etc. we're also used in our Call of Cthulu game.
Any scale issue (and I don't remember there being any) were well down the list of priorities when faced with a hoard of raging cultists of Nyarlathotep backed up by the SAN reducing sight of zombies!