A bit more on the old girl , IF you can find a long bolt head you may be able to avoid rechambering ,They were made to a fairly wide tolerance and any MK1 /number 1 mk3 bolt head will fit ,also your bolt head which is for a CCLE is worth quite a lot of money on evil bay as they are quite scarce, so you will probably come out with money in your pocket. You would need to measure your bolt head from the shoulder to the face and work from there . If I get time today I'll have a look in my reference books for the specification.