Yes & yes, Diameter wise they are a like for like exchange with a +30mm cross section divide by 2 and that is a mere 15mm increase on the inner rim.
Not sure why you have spacers exactly? Is it for aesthetics? A Defender runs a 235/85 r16 tyre as standard so there would be very little to be gained apart from widening the wheel track to fill the arches more but the spacers could be done away with if you wanted as these new tyres will fill the arches much more but in reality it makes no odds apart from another potential point of failure.