Joroas, I'm led to believe the Perry WW2 plastics are actually a different scale to their Victorian stuff.
I have a few figures from the Perry metal Sudan range. I assume they are the same size as the plastic ones (as they're designed to be used together), and they match my Artizan Tirailleurs Sénégalais pretty well, actually. The Artizan are a little bit taller and a little bit chunkier, but not to a degree that would put me off using them on the same table. But these things are quite personal, and one man's view of what is acceptable doesn't always match another's. I've learned this from many, many posts where folks have sworn that one range is miles too big to use with another and I'm left totally scratching my head as to what they're on about.