Torque Converter - help with decision Manco 606c-14

[Jaugesen]

Hello Everyone, this is only my second post, and would still be considered new here. I am from Lubbock Texas, and just got into Go Karts. I have a Manco 606c-14 Scorpion. It currently has a predator 212 hemi with a stage 1 (still has the govenor at this point) from my first post, the advice that I recieved is making me lean more towards swapping the engine to the 420cc predator and just moving the 212 to my Coleman ct200u that still has the 196cc motor on it. Anyway, if I do go this route, I know I will do at least the stage 1 to the 420, and over time bump that thing up in horse power further. This will possibly pass the 16hp rating the 40 series torque converters state they are rated for on the top end of the scale. I have seen 40 series TC's on amazon and Ebay much cheaper than some of the popular go kart websites. Are those same or lesser quality? Is the 16hp rating a guideline with a +/- of a little that it wont be an issue? I would like to have enough power and torque for the 50/50 mix of paved road and dirt/gravel roads that we will take this thing on and still have the torque to climb some minor inclines. What sprockets do you recommend as well. I most likely will need to cut off the hex axle when doing all this. One of the rear tires if rusted to the axle, and if I need to change the sprocket, I will probably need to change the entire setup. I understand that this could mean an entire new fab'd rear end. Or at minimum cutting off the engine plate and welding a new one on. I want the best setup so I wont tear up belts quickly. Do I need to consider upgrading the shocks as well?