Easiest conversion on the planet. I've done a lot of TT Rovers. I like the Tongsheng kit, with the 850 C color display. A 500 watt, 36Volt version would be plenty. Go to the Euronau website, for the kit,and a Samsung battery. If you order the Terratrike Low Rider Rack, and fit kit for attaching it to the Rover, it makes a great mount for the battery right behind the seat. I mount the battery parallel to the best back, to make it easy to access, charge, or slide off, using a Hailong style battery. You will need an extension cable for the speed sensor, (110 mm) as it's usually best to mount the sensor at the rear wheel. Also Get a handle bar accessory mount for the 850c display. I like the Minoura Space Grip SGS-400. Mount it on the left hand bar, since the right hand side has limited space, due to twistshifter. You'll also have enough room to add the thumb throttle on the left handle bar. Cut the existing grip cushion back about an inch. Place the control pad, on the vertical part of the handle bar, just beneathe where the handle is welded. You can then reach it with a thumb easily while steering. I also only use one of the kit' brakes, usually left side too, and retain the Rovers right hand brake for its 'parking function.'. The kits left hand brake will have the cut out for the motor. With torque sensing you could likely not even need the cut out brake. Your wiring harness will go to that left side and make for the cleanest wiring set up, as brake, throttle, and display will connect there.
With torque sensing, it's a dream on these Recumbents as cadence sensing can really be hard to manage, especially if you don't have the right size chain ring. Your wife will love it too. No issues either from dead stops, and can give yourself a boost with the throttle at any time. The motor is whisper quiet at the crank. You'll also end up with one of the lighter weight Etrikes on the market. 56 lbs if it's the x8.
Good luck !