The sketches seem to me to draw on the Helsinki Concert Hall, then new.
One of the problems that also helped put this project into the deep freeze was disputes over the future location of the facility.
If I recall correctly, sites suggested, at various times, were
Ballsbridge (the army barracks site)
Phoenix Park (this one ran a long time)
A site near the then Cattle Market in Phibsboro (Was this the place where the large office block was built?)
Santry Demesne ( somewhere near Stadium, then itself named after JFK, but it has since lost that title in a curious sign of changing times).
Of course, there was never any money for the project, and the closure and demolition of the Theatre Royal in 1962, clearly showed how little appetite there was for big theatre / concert venues in Ireland at that time. It was dead, but not admitted to be dead, for a long time.