It might not be a bad idea for BCB to identify a few players whose skills might be useful for T20. Involve them in HP. Dont be discouraged by age. Work on their technique, fitness etc.
For instance Junaid Siddiqui is probably one of the biggest hitters i ve seen in Bangladesh. The bloke has big shoulders and strong upper body. On top of that he is an exceptionally gifted timer. But he is inconsitent, has a lot of technical issues. But its a 20 over game. A good coach would look to negate the impact of his weaknesses, and work on his strength which is to hit big.
https://www.youtube.com/watch?v=r-auKiFmuiY