Hi larfinboy, sorry about the delay, I've had a pig of a day and simply didn't get chance this morning.
Anyhow, space between the lower part of the alloy heads is approximately 150mm. The height of this inner section is 12mm and the overhang is about 7mm (just under). The distance between the centre of the hole in the base and the spring retainer (the paddle in the middle) is 78mm. The space between the threaded rods (with the heads removed) is about 168mm.
Two problems based on the above and your own measurements;
1. You would need to fashion new bolt down options as your router will not fit with the alloy heads on.
2. Whilst the flat of the router will fit to the spring retainer base, this plastic mechanism overhangs the base - unsprung its around 13mm clearance but when pressed to release the plunger it goes down to around 10mm. Not sure if your router will clear that.
One thing to note it that the underside of the base is not flush with the surface, there are 2 small plastic blocks - my point here is that should the T11 fit between the threaded rods and clear the plunger spring mechanism you could always drill some holes to retain the router base - in fact if you took the base to its most basic form this may it lower profile as well - not sure on this one as I don't have a T11 to hand.
Hope this helps and makes sense.