Lorgar just got released at Forgeworld and I've been thinking about using a Primarch model to convert an Inquisitor in 54mm (though the price point is pretty high, anyways...)
Has anyone else tried this? Or does anyone have a Primarch model and can do a size comparison?
I've not seen them in person, but typing things like "Angron size comparison" into Google Images shows that while the Primarchs are quite a bit bigger than normal 28mm models, they're only around about 40mm tall.
They're big, just not big enough. I'd take your money elsewhere.