I received this info from some T/A guys on another site about your questions:
Differed by team/budget.
Ford wanted they're stuff, so team cars through '69 got FoMoCo shifters, usually HD A/C car radiators, and C-series truck ignitions (pre-Duraspark), etc.
I do not know if Chevrolet used transistorized ignitions.
Independents did use Hurst shifters earlier than '70.
Custom radiators, brass or aluminum, was the norm by '70.
AND
The factory wanted the cars appearing to be stock and with their parts in view.
Aluminum radiators were very expensive at the time so dependent on budget. It was more a weight thing than cooling issue. Most cars ran the biggest factory brass radiator that would fit.
Heim joint shift linkage is a newer thing. It doesn't improve shifting that much and remember these were tough dudes who could wrestle these cars around for 2-24 hours with no power steering. Yanking that lever was a minor event. Also building race cars is about taking weight out not adding it.
MSD was new in 1970 some people experimented with them but they weren't the "breakthrough" for performance gain vs cost/reliability.
The FIA has a historic database you can search for specific cars.
Also, found this comment amusing:
The FIA are sticklers for using their rules to adjust the results to favor their pets. When the lowly Austin Mini continued to beat all the big expensive sports cars on the rally circuit the FIA tore it down until they found something they could disqualify the win. EUREKA - this parking light bulb isn't the one listed - you lose.