I've used dowty washers instead of traditional sump plug washers. Like these on eBay 132585478534 check which size you need before ordering.
I have now received the tap, £ 7 from EBay a tapir and plug tap so not bad.The taper tap fitted straight in and turned easily no problem, the original sump bolt with copper washer is now been fitted and all seems ok no leak, so hopefully I might have got away with it.