Engine drive pulley size

[i967mustang 21]

Does anyone know why the engine drive pulley is so much different on a hydro compared to a 8 speed? What would happen if you used the hydro pulley on an 8 speed or vice versa?

 

[953 nut 55,851]

A larger pulley on the engine of an 8 speed would make it go a lot faster but have less pulling power, th smaller 8 speed pulley used on a hydro would develop less pressure and it wouldn't pull as well nore would the lift be as strong, kind of like being at idle.