Series 3 box in a 11A

I am looking for some info on fitting a series 3 box in my 11a.
The engine is a 2.5N/A ex defender
I have searched previous threads but the info is conflicting.
Firstly will a ser. 3 bell housing fit a 2.5 engine.
2/ Will the ser. 3 box fit the vehicle mounts and prop length suitable.
3/ As for the slave cylinder pipe what is the correct run for the pipe.
4/ Clutch wise will a defender pressure plate and series 3 friction work.

At the moment I have a ser.2a box in (knacked)

Many thanks in advance.

I've got 2.5na, series 3 box and 2a chassis.
Box and props etc are ok. Gear box cross member needs gusset on passenger side cut away to clear slave cylinder.
Pipe can be defender or series 3. Series 3 flywheel fits crank, don't know if 2a one does (I expect so).

Clutch is all s3 9.5".

Many thanks, I can now proceed with the job knowing what to expect.

See here for some photos of what needs to be cut away.

http://www.landyzone.co.uk/lz/f6/under-engine-crossmember-gussets-problem-268885-2.html

Thanks Webley, disc cutter at the ready!