That one looks pretty good. Looking at it, I'd compare the price to the Advanced Adaptors kit. That one is similar, where it replaces the output shaft with a heavier duty one.
JB Conversions is the best one if seen. With that newer electronic speedo control. That one would allow for the longest driveline.
I've never been a fan of the one's the you have to cut your own output shaft. Too cheap. Plus, if you've worked your T/C preety hard, that stock output shaft could be bent.
Omix Ada is out of Georgia. They distribute stuff, they don't manufacture. So I'd try to figure out what manufacturer that one really is.