360 flex plate & torque converter options

The shop has my 360 and they're rebuilding it now. It's a very stock rebuild, nothing special. This will be in my daily driver Dart. I've read all about how 360s are externally balanced and I had some questions in regards to it. This is a 360 LA engine.

The shop has a harmonic balancer for it, but they do not have a 360 torque converter/flex plate. The paranoid person inside me says to get them one so they can check the balancing on it. Am I being overly paranoid about this? I know people switch out torque converters all the time, and as long as they're the 360 style (externally balanced with weights) there shouldn't be a problem. Still, I guess I just want them to ensure everything is balanced on the balancing machine. Thoughts?

If I do move forward with getting them one, my first choice would just be finding an aftermarket 360 torque converter/flex plate combo that would work. Again, this is a daily driver, nothing special! Does anyone have any recommendations on which one I should buy? Most I find are for high performance application and are like $500+. I just want a stock-ish replacement one, or one that would yield more economy/performance. I really don't know where to start for this.

The other idea I had was just getting this and giving it to the shop right away:
http://www.summitracing.com/parts/bmm-10236/overview/make/dodge
That would enable me to use a neutrally balanced torque converter. I guess that's nice for options and everything, but it would raise the price buying it all separate. Again, for a daily driver, i'd prefer to go the previous route of getting a flex plate/torque converter combo. If I DO have to go this route, can someone explain to me how it works as far as ring gear? All the flex plates i've come across have the teeth on them, so when I saw this one I scratched my head. If I get a torque converter to go with it, what do I do for the ring gear? Do I need to buy one and have it welded to the torque converter? Sorry if this is a dumb question, I am not experienced in this area.

Thanks guys.