You are talking about buying just gears and swapping then into your carrier? The difficulty depends on what you have now. If its a bone stock 1.76 then you have to grind the peened over lip then press the pins out. If it has aftermarket pins they should just slid out after removing the retainer. Replacing the needle bearing is a simple but tedious process, it's like putting the bearings back in a u-joint. I put a pin in the gear and pack it assembly lube then start putting in bearings it it's full, again it's not hard just takes time. Now as far as if it is worth it, The carrier of a 1.76 planetary will take more power than the gears, so it common to put a 1.80 gear set in a stock carrier.
Hope this helps, Dan