Slickshot.
The best model 1873 reproduction, to my mind, is the Codymatic ... he starts with a Uberti '73 and then slicks it up with all the fast things ... including the short throw lever and an aluminum carrier ...
It seems like good sense to:
1. Get all the good stuff put on by one person at one time ... this allows him to tweak each thing that changes once one puts the speedy stuff on. It is kind of a given that one thing will effect the performance of another ... and he can 'fix' the whole rifle to get you a good end product.
2. You get the warranty for the whole gun, including all the 'go fast' stuff. Some warranties will go so far as to require the original parts be in the rifle or the warranty is null and void ...
3. The price is more than a stock '73, but cheaper than the total if you bought all the 'go fast' stuff after the purchase of the rifle.
One Caveat: NCOWS does not, I believe, allow competition with a short stroke kit or aluminum carriers . So if you plan to compete with NCOWS, this would not be an option ....
http://www.codyscowboyshop.com/