Try Tony Leamon - http://ajleamon.co.uk/shop/?product_cat=ppu - he has the PPu 8mm 198gn bullets listed on his website and shoots fairly regularly at Severnside so is worth a try.
He has a trove of unusual bullets on his shelves. Evenings are the best time to get him on the phone.
Hope this helps.
Adam.
Edit: He also has Hornady Interlock RN 8mm 170gn bullets in stock.