Boomstick

I can't find anything for the original UHD. There is one for the Echomap Plus 73sv, which I think is the same but I'm not 100% sure.

Your best bet is probably to call Garmin directly.

On a side note, I stopped taking the display unit out of the base after having some pins break off. In my case, the problem was made worse by a sun shade but I've heard others who have the same problem without the sun shade. But given how it's on a kayak, it's not a big deal to leave it in the base all the time.

If you do decide to upgrade, the GT56 transducer is a significant upgrade over the GT54 in both clarity and range, and the 93sv UHD2 has a few more pixels so you can enjoy the added range and clariyty.

My kid has owned a Voodoo, and now a Zulu with pedals. At $2200 or so with pedals, that's a pretty good buy. Kind of crappy pedal system - the left pedal screw is not reverse threaded so it can fall off, carrying the provided allen wrench for it with you at all times is required and I recommend using blue loctite to help keep it in place. The hulls are solid. Probably the cheapest pedal drive kayak I can honestly recommend, and probably the best customer service in the business. If you post a question in the Facebook group, the owner of the company may answer. Or if you email them, you may get a response from Kevin himself.
 
Neither are fast paddling/pedaling (probably average), but they're decently stable as long as you don't lean - the V shaped hull means if you lean, it goes. Not a problem for an experienced user.
 
I didn't see too much of a difference in stability, but the Voodoo is supposed to be more stable and the Zulu is supposed to handle chop much better, I'd water the latter is probably much more significant than differences in stability.
 
You can sit on the top of the back of the seat to sight fish.
 
I would probably go for a Zulu or maybe Voodoo if you plan to motorize over the Guru unless you have specific need for the extra storage and weight capacity. The Zulu with nothing on it feels much heavier than my Old Town Bigwater with all my stuff on it, maybe largely because of handle placement.
 
If you plan to get pedals, then you'll definitely want the Zulu. The Guru's fin drive has a ton of complaints about the pedals constantly falling into the plastic, and no known solution at this time.

The other thing to note is the Zulu's front hatch (or Guru's front and rear) takes on a lot of water. I left it out in a heavy rain storm and the hull was 80% full of water, no joke. I'd keep a bilge pump in the hull whenever you go out. The Voodoo's hatch didn't leak that bad, but it's also small and you can't get larger items in it.
 
A few accessories that are a must have with these:
 
The Kaku seat bags let you store things on the side of the seat, very useful.

The YakAttack Double Header to hold your paddle off the kayak
https://www.yakattack.us/doubleheader-with-dual-rotogrip-paddle-holders/
 
The 3.75" YakGadget LowPro tray fits under the seat for storage. For a flat kayak, this can keep things like your water bottle from falling in the water. You can get tool storage trays cheaper, but in the long run this is worth it.
 
https://yakgadget.com/collections/storage-accesories/products/lowpro-tray?variant=37346174501021
 
When I tried my kid's Zulu last year, I was probably 335lbs at the time and it stayed above the water line with me and all his gear in it.

Tubes, Roboworm straight tail & alive shad, TRD and rage tail craws

I would definitely prefer 3/8oz baits on that rod. For 1/2oz spinnerbaits and chatterbaits, I generally use a rod rated from 1/4 to 1oz. 3/8oz works on either.
 
Something else to consider is you can throw a spinnerbait with no trailer or just a trailer hook, but with a chatterbait you'll always have additional weight from a trailer, often a Keitech. So a 1/2oz chatterbait plus a trailer could easily exceed 3/4oz. Even a 3/8oz with a 3.8" Keitech would be nearing 3/4oz. A trailerless 1/2oz spinnerbait should still be under 3/4oz, but a slightly stouter rod would still be preferred for that although not required.
 
Your cheapest bet would be to start at 3/8oz before buying a new rod. If you're pretty sure that these are presentations you're going to stick with then perhaps a stouter rod is worth it. On a side note, that stouter rod can also throw a senko with a 1/4oz weight pretty well and 3/8 and 1/2oz jigs, 4.8" Keitechs on swimbait hooks and a whole slew of other stuff and is probably one of the most useful rods you will ever own.

Assuming you're throwing a 1.5 sized crank, I like moderate if there's no grass. As soon as you introduce grass, a M/F or MH/MF becomes more ideal. Most of the time something moderate is fine.
Personally, I would classify that as a Medium moderate rod by most manufacturers standards - and yes I agree that's a good one.