ZF-LS: Magnus Mate?

A recent trip to Target reminded me "oh yeah... I've got a Zombie Fighter Longshot I was working on" when I saw the 2-Pack of Zed Squad Magnuses (Or Magni?) on the shelf. Sadly, there wasn't a Longshot to compare the colors with, but I figured it looked close enough.  I picked up the set and went home to rekindle this idea I had to integrate these two together.  I had thought the blue on the ZS Magnus would match that of the ZS Longshot.  ...Well... not quite!

Turns out the ZS Longshot is more of a greenish blue and the ZS Magnus is more of a blueish turquoise.  Or aquamarine, depending on when you were born.  This leaves me in a bit of a tizzy about this whole idea in the first place.  I've had a long time to ponder this, so let me break it down for you real quick.

My original idea was to made a Stefan-based "Zombie Fighter" out of this ZS Longshot.  Make it tacti-cool, make it survive the hordes of the undead, make the Xplorer Vanity Club put their seal of approval on it.  I wanted to build up an awesome Longshot with a nice strong spring and a shotgun-style pump.  Then got to thinking about doing an integration with the Magnus.  Having a Stefan Slinger on top with a grenade-launcher-esque MEGA Magnus under the main barrel.

Regardless of whether the colors will match up, I wonder if putting such a heavy blaster on the front-end of the Longshot will be a good idea.  If I were to attempt to balance things, I would need to add a bit of heft to the stock of the Longshot (which is easily possible) but then I end up making the entire rifle heavier.  There could be a good and bad side to doing this, but then the question also comes to priming the Longshot itself.  If I want to have a strong spring in there to sling out Stefans with deadly accuracy, a pump-action prime would probably be better to handle a high-load spring than the stock bolt-action prime.  I have not had good luck with strong springs on a bolt-prime before (I remember the Longstrike Massacre kit...) so the addition of this Magnus poses two possible issues.  Three if you count my OCD obsession with things matching up.

For now, my plan is to focus on the Stefan side of things.  I think I can answer my own question if, by balancing power with a bolt-prime, I can achieve the sort of performance I'm looking for without the use of a shotgun prime.  Then an integration wouldn't seem like a sacrifice to the original goal of this project.  If I can't, I'll just go with a shotgun prime and do away with the integration idea.  What say you, Nerf Nation?