2nded on 5spd conversion.
Its all scale of economy.The reason so many people dream and dont end up following through is because everything for the 126 is either NOS or bespoke.
as an example doing a wide body conversion on a jap s13/180sx etc guards bumpers skirts can all be had for around $1000NZD from multiple sorces making it a viabe proposition.
a member on here does his set of guards only for around triple that , Not at all an unreasonable price for a 1 off made to order set up, but by the time youve fitted painted and added wheels you have spent almost the cars value again

or the price of another interesting wagon.
same with 5 speed conversion.
If there was an off the shelf kit $$ inline with what you can buy a converson for skyline turbo/lexus ,$3 k or so bolt in there would be alot more manual SECs around .
Sadly it will never be viable to mass produce 126 performance parts because there just arent enough people that want to put there money where their day dreams are.
last weekend I picked up a 16 valve twincam manual widebody 944 porche in better condition than my SEC for $5k nz around a 2 thirds of the cost of doing a manual conversion or a decent engine conversion or even a good quality paint job.
That said i still spent hours angsting about what major mod i want to takle first...