New Bearings/OLD hub

Easiest way to remove the inner cone/cup and seal is to first remove the nut and washer, then determine if the nut will pass through the outer cup, if so then start the nut back onto the spindle by several threads then, using the hub like a slide hammer, rapidly pull the hub towards You. This will leave the inner cone and seal on the spindle and usually without damaging the seal.
If the cones and cups have no pitting or galling I would pack the bearings and put them back on. The old seals can be reused if they are not hard and cracking.
Cones and cups will have numbers stamped into them, usually they will be Timken bearings.
If You want to go to electric brakes then the drums and backing plates will need to be replaced. If it has drums then it may be possible to find backing plates and electric brakes that will fit Your drums.
I would try a trailer supply store to see what they have in stock.

If the seals are pliable and not cracked but get slightly distorted from removing them, they can be placed on a block of wood and tapped back to flat again.