If the Original 63 is the same pickup that was until recently called "Original" and before that "Original 62" (and I'm pretty sure it is), then yes, it could be a nice choice, depending on where you wanna go tonally. The Original has more mids than the rather scooped V-Mod pickup in your Pro and also slightly more upper mid bit than the GZR. I like the Original a lot but the added upper mid presence can get a bit bright/clanky with some basses/strings. For MY taste they work great with alder+rosewood and mellow strings but maybe a tad too bright with ash+maple basses and/or very bright strings. The Original is leaning a bit towards what I would call a "punk rock P-bass tone". Perhaps more of a 70s Fender vibe than it's current name would suggest...
Don't confuse the Original 63 with the Pure Vintage 63, which is possibly the most boomy P-bass pickup currently sold and probably not what you want. Fender pickup names are confusing. People still get the "Original" and the "Custom Shop 62" mixed up and it's over a decade since the "Original 62" changed it's name to "Original". I can see a lot of confusion between the "Original 63" and "Pure Vintage 63" in the future...
It's also funny how Fender's marketing will tell you that all these three different souding pickups nail the early 60s tone... The Custom Shop 62 is probably the closest. The PV63 is WAY off.
Btw, the Fender Custom Shop 62 is tonally kinda between the Original 62 and the Pure Vintage 63 but leaning heavily towards the Original. The CS62 isn't nearly as muddy and bloated in the lows as the PV63 but not quite as much presence in the upper mids as the Original.
Of course there are lots of other great options too. Some of my personal favourites are Kloppman PB63, The Creamery '58 and Lollar (standard wind).
If you're currently using the solderless wiring kit with your GZR another option might be to replace the .022uF tone cap with .047uF. This will give you a MUCH wider useful range on the tone control (and also more "vintage correct"). The tone cap in the solderless kit is a tiny surface mount component so unless you're comfortable working with those it's probably easier to replace the entire wiring, pots and all.
