Installing a John East preamp and new Fender noiseless Jazz V gen 4 pickups

It's a Jazz bass and you've mentioned soldering, grounding and shielding. If you have no prior experience, and I say this because East preamps don't come cheap, I would use a pro, maybe you can agree to a slightly lower price but remember you want the best job possible so your bass is shielded, grounded, and most of all you're able to exploit the full power of that preamp. You get what you pay for. I don't know where you're located so can't suggest any businesses that might be useful to you.

 

I'd say it's realistic. John East preamps are mostly solder-free setups. The cleanest uninstall of the old preamp would require the soldering gun, but you can always nip off connections instead if needed.

Likely, you'll need to cut/desolder the leads to the preamp from the pickup and remove the connection from the batteries. The jack, I'm not exactly sure what the East comes with, but if they both use the standard 1/4" stereo setup, as long as the wires are long enough, you should be able to use the new one with the jack plate.
If not, keep an eye on what the old jack connects to so you can adapt it for the UniPre connections.

When you've removed the old preamp and pickups, the only real connections that should be left in the bass are the grounds and batteries. There may be multiple ground wires or they may have grouped them together, but they will need to be connected to the UniPre.

I'd install the new pickups, connect them to the preamp connections, connect the grounds, batteries and jack as needed, then install the preamp into the bass.

I installed an East into my old Jazz Deluxe 5 many years ago and remember that the battery clip included was more difficult to deal with than just leaving the original in place and using the existing connections to attach to the East.
If you have any trouble or concerns, feel free to post pics before cutting or connecting. But honestly, part of the beauty of these super-exotic preamps was their ease of install.

 

Will you need to strip the ends of any wires? Having a wire striper with small gauges will be really helpful. I'm a strong proponent of the right tool for the job...

This one's less than $5.