If you call Chris as listed in the classifieds he has a whole XBR engine for sale. It looks very tatty from the outside, looks like long term salt corrosion. However, when picking up some of the XBR bits from him yesterday we did turn the motor over and it seemed OK. It is difficult to know for sure without pulling it apart but I would say worth a punt for £40.00 for the whole engine. Chris did say £50.00 but bearing in mind the comment I make above I would offer £40.00. If the motor has covered what the clock shows then it has covered circa 45,000 kilometers. Even if you only used the top end and junked the rest it would still be a cheaper alternative to new parts?
Good luck,
Andy