Usually an inexpensive import bass has lower grade pots and input jack from the factory. The most common first upgrade are the pots and jack. If you are going to upgrade the pickups and will have it all apart anyway, I would suggest you do the pots and input jack. As you suggested, if you buy a new pickguard, you can do the assembly separate from the guitar. I always mount the pickups separate from the pickguard in the body and then make the last two solders to the assembly before mounting to the body.
I would recommend using CTS pots and switchcraft jack which are available in kits at many of the online stores for less that $20.
Last edited by soflbass : 08-09-2013 at 01:25 PM.