Ultimately this is what I ended up with. My original intent was to have that model standing on top of a recently defeated Killa Kan. As it turns out, the original killa kan took up far too much of the base and was too tall. So, plan b was to cut down large portions of the torso, and model it to look buried. Now the Contemptor is striding across the long-dead Killa Kan, without even breaking stride. I like to imagine this pose suggests it is running forward and spraying a nearby enemy with the heavy flamer before assaulting them. Not pictured here are the multiple times I had to disassemble already-glued pieces once I realized I wouldn't get the pose or look I was going for.
Thanks to MSP from the SA forums for the tip!
I had originally planned on magnetizing both the arms on this model. (They're currently attached with poster-tac.) But I'm now thinking I will at most magnetize the gun arm. I much prefer the look of dreadnoughts with one (or better yet two!) close combat arms, so I saw no compelling reason to magnetize the current combat arm. Besides, if I do decide I want a dual assault cannon contemptor for example, I guess that would mean I'd just have to buy another! What a shame that would be...