The best advice you will get for the BV20 type lathes would be on a forum intended for such a lathe.
You will need to change the arrangement of the gears for fine feed, swap big for small, small for big.
Other gears in the kit are needed for a fine feed arrangement, if I remember correctly, as the ID of the gears are different.
Possibly also you will need another banjo to accommodate the gears for the fine feed arrangement.
The type of layout used on these lathes are a commercial favorite of lathes from the sixties onward, but the gearing is model specific.