Would add QED Motorsport to list of suppliers, handy website, search under c20xe, and helpful if need advice. As mentioned there a 2 types of timing belt, round tooth type for earlier engine block and square tooth type for later, would suggest from age of yours that it will be later square tooth type. But when i pulled my engine out last month found it to be a mix and match with earlier coscast head and later block, so as well to pull cambelt cover and take a look - SBD guide here -. Would recommend that repalce water pump and pulleys while about it, especially if don't know when last done, can purchase a cam belt kit which has everything you need. QED provide stuff like filters, belts and gaskets too but worth making note of part numbers as remove them and keep a record for next time, most can be sourced through local motor factors just stick with reputable brands. Good luck.