I have built many of these transmissions for CTD trucks at my shop. I recommend the triple disc torque converter for sure, especially since you have a Smarty. The TC is the weakest link of the trans. You can get by without the billet shafts and flexplate at your power level. Id install a shift kit or better yet a performance valve body if it is in the budget. Use a quality performance kickdown band in your rebuild. No Kevlar junk. In most 48REs I've had apart, the factory kickdown band was worn down to the rivets. One more thing, Install an upgraded GM style Governor pressure solenoid to help prevent future failures from the p.o.s. factory unit. FWIW, I use Suncoast converters and valvebodies.