>>1845318haha wow nice dude. That was my rec. As a 6'2 manlet i personally can't put enough stock in buying huge bikes for myself i can't imagine being taller and dealing with bikes so good that you found something ridiculous like that.
It's excellent that you like the leather saddle, that also alone makes it worth it. It will only get better.
Ok so for modifying it, I would recommend you get some used old mtb parts. That style of stem is semi-notorious for breaking (maybe not that exact one but still- look up 'atax death stem'). Plus it probably has a 26mm clamp, not 25.4 so would have to be shimmed to fit straight/cruiser bars.
Any 1" mtb quill stem, size to fit, would be good. That is the most generic size. There are 1" and 1 1/8" ones it's very easy to tell them apart. Even better one with a cable stop for your brake.
Go hit up a use bike shop/ co-op.
Aliexpress do also sell cheap/ok riser bars and cruiser bars but don't buy a stem there.
Used levers would also be best. You want ones designed for cantilever brakes (short pull). You can differentiate them by measuring this pivot-cable anchor distance c-c. <30mm is short pull >30mm is long pull (v-brakes, disc brakes). (credit to anon for the picture). The claris brakes pic rel (which have a dual cable anchor position for both pulls) are probably the best new option but it's more money than you should spend.
It would also be easy to convert to bar-end shifters, yes. But do it later. Change one thing at a time. Service other stuff too. That bike with it's archaic narrow gearing suits DT shifters even, just don't shift much. And you would get better braking preformance from the centerpulls if you converted them to modern cartridge pads, with angle adjusting washers, so you can toe them in. I would do that before modifying the gear shifters. Also service the bearings
