I have not thought about it in that way. I have been rebuilding them on a turn around basis for years. Looking at what parts are NLA I'm thinking exchange or turn around is the best way forward. 

The shift housings have either plastic or thin steel backed bushing. These wear and the shift rod wears into the housing. Finding the OE bushing is hard and if housing is worn they won't work. By boring the housing to accept a new easy to find .625 oil-lite bushing and flipping or replacing the rod lost motion is greatly reduced. 

Installing a grease seal in the forward opening ( kind of like the Inno shifters ) stops trash and water from getting at the forward bushing. I keep new and rebuilt shift eyes. The ones I rebuild use a slightly harder alloy for the shift eye bushing. This also removes free play. 

The shifter housings that have been converted to a quick shift at some point in their life have the pins removed and the pin holes tapped. Some have had a little grinding done to clear the shifter. While I'm no fan of quick shift kits I would set up a couple to get rid of the parts. It is common knowledge that anyone can shift a mini faster than the synchros can deal with. A more correct name would be short shift, just less travel between gears and if you respect the synchros, should be fine. Also the MSC kits have a chrome shifter. With shifters NLA could be a solution.

I would also consider exchanging just the housing and shift eye as they are the parts I have to machine the balance is just clean up, paint and assemble. Shoot me an e mail ( info in profile ) and we can work it out. Steve (CTR)

How much does a fully built setup cost? What are the primary benefits? I'm interested.

Metro shifter rods are different Steve but i can't recall 100% if they are longer or shorter but i am thinking longer,

I have gotten behind on rebuilding shifter units. Seems with several units that were set up as quick shift ( pins removed ) I have eight rod change shifters. I have a couple of kits from MSC to set up a quick shift unit. I have the reamers with bushing to open the housing bores to .625. I then press oil-lite bushings in place and run a .500 reamer though. I clean glass bead and paint the housing and add a .500/1.00 grease seal to the front opening. It is common to flip the shift rod end for end polish the bearing area ( if not rusted ) and use it that way round. I also have set up the shift eyes and bored then out till all wear marks clean up. Then machine a alloy bushing with a shoulder, press it in place and hone to fit the ball on shifter. The other option and I have only done two of them, is to bore the shift eye to accept a spherical bearing and remove the lower ball from stick and polish the shaft. I need to order more of the bearings if I want to do more of them. I have ordered a length of .500 cold roll to make up new shift rods for those with wear on one end and rust on the other. 

While lining everything up to paint the steady bars and shift rods I notice I have two sets that are 1/2 inch longer than the rest. I take it they are for the later cars with the forward mounting sub frames. My question is are the Metro shifters also 1/2 longer or some other length?
Steve (CTR)