Power x feed.
I did something similar on my Marlow mill, kept it simple and used a geared brushless 12v DC motor (Vexta) and speed controller I picked up the lot on fleabay for sub £50.00. Main problem was getting the belt drive system right to give a reasonable return speed but still be slow enough for some of the large end mills (40mm dia). Did not get it right the first time as it would not go slow enough so added an additional belt.
More than enough power to move the table when taking large cuts with large end mills all be it aluminium with paraffin to keep the chips from sticking to the cutter.
Used a simple dog clutch to disengage the drive when using manual "simples"
At present all my kit is buried with a load of boxes in the attached garage of the house we have just moved to, waiting on planning to turn it into a garage/workshop 7m x 4.5 insulated with heating "Luxury"