David Manners Group (DMG) can supply a good quality kit for this job for about £60 (I bought one, not fitted it yet).
Try here: https://www.ebay.co.uk/itm/Mazda-MX-5-Cam-Kit-with-Water-Pump-Save-over-10/253210881700?hash=item3af48b6ea4:g:~-0AAOxyVLNS18eK