Theodore Bruckner and Reaper as a Space Marine Bike Captain?

I need some advice, but first boring non-hobby stuff.

So I am still recovering from pneumonia, on the antibiotics and until the cycle is done I can't really paint or convert (due to tremors). So sorting through old ideas, trades and bits boxes is what I am left with.

 

Great model 'eh?

I picked up Theodore Bruckner and Reaperin a trade a while back, to go with the Cyber-Cavalry and my Kor’sarro Khan & Librarian conversions. He's been laying around for a while and maybe now is the time to start planning out his introduction to my army.

 

So here is the problem, he is HUGE. I am using the Dragonforge bike bases, and even Jeff's large bases seem small compared to him! 

 

So the question is..

1. Use the Dragonforge 40mm x75mm base and accept the overhang, kind of like Jetbikes
2. Use the Dragonforge 60mm x 100m attack bike base (Huge, but might work)
3. Use the provided Chariot base which is 50mm x 100m
4. Or ....?

When I posted this on my Club forums someone suggest cutting down Reaper's body a bit to make it fit, and I really don't like that option, yes it will correct the size, and be closed to the Empire Demigryph Knights I was hoping to convert into a Command Squad but it stills feels like a bad idea.

So looking for some advice before I start adding Bionics and converting Theodore to be Space Marine in Heresy era armor.