(part quote)
If there is a complete cable shift kit for the 352 transaxle please let me know. Otherwise I am leaning towards the complete rebuild of my OEM shift tubes with the parts I can find and refurbish what I need to.....unless I can find a cable system that someone has engineered for the 352.
I also have a 352 and have looked through many cable shift versions but yet have to find one for the 352. I bought an old Toyota lever assembly as that looks as if it will work but my enthusiasm for the project is low at the moment. When my OEM shifter becomes sloppy again then I think I might have a shot over one winter but as everyone has said, it will be trail blazing.
If you can get UJs to fit these days then a rebuild is your easiest option, not least because the manual tells you how to set it up. All joints need to be really tight although you do need some movement in the rubber bush mounting to the engine/clutch area and as has been commented, too tight here will transmit vibration to the gearstick.
If I had to list improvements in order, I would go;
1. Base of gear Lever to front selector shaft - sideways slop here is not good at all. Probably the most significant area.
2. End connection to gearbox UJ
3. Centre UJ and then finally the adjacent mounting point.
You can fit rubber steering rack bellows to the joints afterwards which keeps out dust/rain, I used the "universal" bellows and cut to size. It isn't a perfect seal but better than being open to the elements.
The reverse detent is probably fine on the Renault but so easily overcome on the Lotus that I used to think the spring had fallen out or something. And you only need to miss 2nd once to lose confidence in those changes. Probably the mass of linkage or leverage has some effect, I don't know but anything to prevent slipping too far across the gate is good.
Peter Boedker on here has manufactured a very neat system for lock out which is similar to some modern cars if you want an off the shelf solution. I opted for a home made sprung lever which just adds as much resistance as you want by the spring selection. This still operates as standard without lifting the lever/gaiter, primarily because I wanted the car to look the same externally and it's completely hidden by the standard gaiter. Plenty of options but I'd urge you to do something in this area whilst it's all apart.
Brian