Kit-Bashing Corsair Reavers

Hey all.

At some point in the near future, I hope to get a box of Guardians, Dire Avengers and Windriders for a single purpose: to kit-bash two Autarchs - one on foot, and one Skyrunner.

Now, since I won't have enough parts afterwards to make a full squad of Guardians or Dire Avengers, I've come to the decision that I'll kit-bash a squad or two of Corsair Reavers instead. Now, for the most part, I know what I have in mind:

- Most of the Guardians armed with spare Shardcarbines (got plenty of them from the Scourges sprues).
- Two Guardians armed with Heavy Weapons (weapons to be decided)
- At least two Dire Avengers as the basis for Felarchs

Before I go for it, I could use some advice on some aspects:

1. How difficult would it be to convert a heavy weapon from, say, a Wraithlord kit for one of the Reavers to carry? Has anyone attempted it?

2. Any ideas on the back piece? I want to do something other than the standard antennae on the backs of the Guardians armor. I've seen a few with capes that look cool, but I'm open to other suggestions.

I ask both of these questions because I don't really want the jump packs that come with the Forge World kit. And I have a lot of heavy weapons left over from other kits that I want to make use of in some way.

Any and all suggestions on the subject are welcome.