These drawings show the changes that need to be made to fit bearings on the lateral and longditudal forks on the Bensen head.
The forks are different in shape from the original and will need remaking if you already have a standard head,but the bearing centre can be reused as it only requires two flats milling on it.
It is best to make the forks first and fit the bearings then machine the trunnions and fit to the bearings.  The bolts through the trunnions need to be tight enough to make sure that they do not rotate round the bolt.