If you've never used a centrepin before, try something with a reasonable price tag, decent performance and steady resale value. I'd suggest either an Okuma Sheffield or Aventa Pro. Plenty of long term centrepin hoarders, even when their tastes run to the very expensive, still have an Okuma in their hoard.
The chances of getting the "perfect" pin for you first time are rather remote. It takes a while of using centrepins to work out what you like and need, but you've got to start somewhere. Those preferences may well develop and change over an extended period of time and you are unlikely to come to the same end result as another centrepin angler. It takes time to work out preferred diameters, widths, weights, ratchet switch positions, bearings or true pin etc. I've settled on true pins of 4.5" diameter and 1" width. However, that doesn't stop me owning and using others. I've yet to find a single reel that provides every feature I'd like to have on a centrepin. At this point in time, I reckon that a three way hybrid of a Young's Atom (true pin/anodized colour), Super Lightweight (weight) and River Specialist (ratchet switch position and type) would possibly be my ideal, especially if Chris Lythe could make it for £500 in a month or two!
As you are trotting with a longer rod that's not especially light, I believe that you won't be particularly well served by paying through the nose for an Okuma Martin Bowler. The only non-cosmetic difference between that and the Sheffield is weight. You'd be paying out for a weight saving that may offer no significant benefit on a long rod. It may even leave the rod feeling a little tip heavy.