I have two Tamiya 1/35 Tiger Is in the stash that I paid $75 for. I'm referring to the older, non IR, 27mhz ones.
There is no parts list to give you until you know what tank you want to convert. Space is the prime concern in 1/35 and a gear head motors you can squeeze into a Tiger won't fit in a Pz I.
Second major obstacle is the tracks. Links in 1/35 don't behave like they do in larger scales and with the size limitations come strength issues. One binding and they snap. You're best bet would be to find a kit with the rubber band tracks or the largest link available, like a T-34 or Tiger.
I'm guessing Clark didn't go ahead with the conversion kits because even as a unit, there would be considerable skill needed to install correctly and they probably don't want the headache of having to solve a bunch of issues. I have the scale 35 kit for the 1/16 Panda 35(t) and while nice, their gearboxes won't stand up and the beautiful kit tracks really aren't up to the challenge. I have a special pin drill that can be controlled down to a few revolutions so driling out the hundred plus link pins wasn't a problem for me, but the end product is not designed to move.
I'd start with choosing a kit and working out what motors you can fit and what tracks you'll use. After that, you can choose the next step, a programable Tx so you can V tail mix two escs to control. You'll need car escs so they are reversible and really small ones to boot. And a receiver and battery and that's just to go forward, reverse and turn.
If you look at my video again, you can see the Rx and battery just hanging out. And that's a sizable 1/35 box of a tank. Tamiya did the hard work by the end gearing, suspension and track links. I can barely get the basics in there and I'm not stranger to conversions.
Look at this TC, he has two servos to control the head in his chest and that's a heck of a lot easier than a 1/35 hull:
'm not trying to discourage you, just want you to be realistic. It gets very expensive by the time you start adding up all the parts, Tx/Rx, battery, servos, escs, gearboxes and then all the styrene stock and hardware and soldering supplies. It's a lot of money and work, if you add it all up, the $300 on the Tamiya may be worth it.