Then you have a 4" bore cylinder. A lot of modifications have been made if this used to be a 50 ton press. At 2000 psi you can expect about 25,000 lbs. force. You should be ok with 5HP. You will still get the pressure and flow from your pump to handle anything you will be doing at home.
EDIT. Cutting your HP in half is also going to cut you work load in half. You really need a hp per gpm to get full capacity.