The Sanguinius is actually standard scale, but it looks like the Bloodthirster has been heavily modified from head to toe. The actual GW/Citadel model range does not carry the large scale busts, but Forge World has several, and their quality is beyond comprehension. Pricey? Yes. Worth it? Very much so, for the collector.
Like you, wolf, I've been playing WH for over 10 years now. Started w/ SM, then Chaos SM, then IG, now doing Eldar. You've gotta love the Wraithlords, unless you have to fight them.