Here's a WIP of my Land Raider Achilles. I will be using this with my Night Hawks (as per the fluff). Anyway you can see I have removed the front assault ramp and replaced it with a mural from chapterhouse. The front includes a rhino panel which ties it in well with the other 40k vehicles. I added a shadowsword megablaster to the front to count as the thunderfire. With that gun's ability to put out tons of hits with blast templates, I think the gatlin will be suitable.