Yes, we are all quite familiar with the Greenidge/Haynes combo.
Then there was the outstanding Sir Conrad Hunte, fearless Freddo, etc. Some even consider Kanhai an opening batsman considering how many times he came to the wicket so little runs on the board!
If taking batting pairs into consideration, Fredericks and Rowe in the mid-70s would be my choice. They only opened the batting 14 times but put together seven 50+ partnerships and averaged 68. Before my time, but Rae and Stollmeyer should also get some serious consideration.
If individually, Fredericks and Greenidge, who also formed a pretty formidable opening pair prior to the Greenidge and Haynes glory years.