Doesn't the Israeli Achzarit have similar layout to the last version?
http://www.nimda.co.il/image/users/1990 ... id=9627670
http://files.radioscanner.ru/uploader/2011/achzarit.jpg
Also, what you could do is put the engine on the front bit. The power pack on the 2 first ones looks a bit large to begin with (assuming the vehicle isn't as ridiculously flat as Russian IFVs and APCs tend to be); what you could, maybe, do is put the power pack to the right and partly under the gunner, especially since he's going to be in an elevated position anyways. I'm assuming the turret isn't a full RWS? Is the gunner moving with the turret? If yes, I think you'll need more space than just his width with gear - the last option could be doable but not very likely. Also, is the gunner offset in the turret? Are the guns offset?
Also, exactly how are the drivers supposed to get out? Via roof hatches or hopping over their seats?
I put together a quick modification in Paint. The last one is obviously mine, sort of showing what my ideas would look in practise.
If you need more space, you could easily squeeze in a few more seats. Or lengthen the vehicle.
While doing research, I was kind of puzzled by the claims of the Sisu Pasi (Patria XA-180 and -200) holding up to 18 troops. For example,
this would look extremely cramped with that many people (I count/estimate about 9 people). Same for the pics of XA-200 interior
without the people in it. But then again, the XA-180 series seems to have less "individual" seats:
http://commons.wikimedia.org/wiki/File: ... urku_7.JPG
http://commons.wikimedia.org/wiki/File: ... %C3%A4.jpg
Best quote found while doing research:
Also dismounting from BTR-80 is like dismounting from clown car IIRC.