I fitted a replacement pickguard on my P7 (the stock one was de-laminating), and I also changed the control knobs for chrome one’s. The pickguard was from Jack’s Instrument Services in Manchester, I’m really pleased with it and it looks a lot better than the original. (See photo).
I wasn’t keen at all on the stock black plastic control knobs, did Marcus really sign off on those??
The only other thing I would change (at the moment) is the string tree, I like the look of the one’s you’ve fitted and shown on your photos. With regards to the tuners and bridge I think the stock items are fine, not 100% sure on the pickups, even though the bass has a “P” split pickup at the neck, to my ears it doesn’t quite capture that Precision Bass sound? Anyway I’m leaving those for the moment, but if ever EMG bring out a Geezer PJ set for 5 string basses I would get a set without hesitation! I’ve got some on my Precision Bass and they’re brilliant (IMHO).