Found a place that does Dry Ice Blasting, only 2 miles from my house & even more of a coincidence, is a friend of my next door neighbour. Further investigation is required to see their charges for underfloor treatment & I'm interested in getting the gearbox I bought from Goldtop done as a trial piece.

https://www.dryiceinnovations.co.uk

Will give an update as & when I have any results.