Thanks everyone!
After posting the last update, I thought to myself "why would I not convert the scouts too? I'm pretty happy with the comms specialist, why don't I do that to the sergeant too?". So I stopped finishing II Scout Squad, brought out some tools and plastic scouts, and went to work.
And now I have two sergeants, ready to rumble (well, after they get some paint on them). One of these will have Kelborn's Hradin Voroka's head and become I Scout's Sergeant. The other will become II Scout Squad's sergeant. So sorry, but II Scout Squad is not finished yet.

UPS also came by and delivered the thudd guns I ordered! Yay! I while back I had the idea to use them as Thunderfire Cannon stand-ins. This was the concept sketch using my awesome powerz of microsoft paint:

So I went to work on them, I simply sawed off the details of the inner parts of the Kataphron Battle Servitors, filled the gap behind the upper axis with putty, and pushed in the axis of the gun's carriage. Other than a pin, it's a very easy conversion.

I also slightly shortened the front shield's lower part on both sides.
It´s pretty much good to go.

Cool huh??
I´m very pleased with how it has turned out!!
I have three of them, but sadly only one techmarine to go with them. Perhaps I'll paint one this weekend (as the GF is out of town). I plan on magnetizing the whole gun to the base for gaming purposes - no sense in limiting it to certain places... 
Anyway, I hope you like the scouts and the thunderfire/thudd cannon! C&C welcome as always!
Cheers!
Replies:
@FLint13: Thank you! The black is growing on me indeed. I've started using GW Skavenblight Dinge a lot, mixing it with AP Matt Black and VMC Off White to darken or brighten it. Pretty cool to work with. The beard came out wonderfully indeed - looks just like mine. Not as glorious as your GIF dude by far though.
@Alpharaz: Haha cheers buddy, you're most welcome. I'll be using Tion as Telion with Ultramarine tactics, because it's not possible to use him with Imperial Fists tactics. This means I'll have to ally a small Ultramarines force (in yellow colours because cheese
), consisting of Telion, one scout squad, and a heavy support choice consisting of three rapiers with quad heavy bolters. Telion then will give the rapiers Rending. 18 TL S5 AP4 shots with rending, baby YEAH! It's called Swiss Cheese because it cuts through your stuff like an army knife.

@GrandMagnus: cheers buddy. They fit pretty well. Only some slight dremmeling to make room for the Scion necks and you're done.
@Leviathus: Don't they? Thanks buddy!
@Barrabas Sogalon: yeah buddy I feel your pain. it's even colder in Norway than it is in Northern Netherlands, right? Hopefully the Africa for Norway initiative will be ready for you guys this year too.