For me, it seems that the mid 70’s hot tip was still the Racer Brown SSH-25 or 44 hydraulic cams but the Purple Shaft cams of similar lift were gaining in popularity.
The GK cams like the A5H288B were kicka$$ cams too.
Had a Mini Express in my SS car in 1973, then went to the GK roller late that year and all of 74.
It’s a shame GK closed shop, Tewles and Brookshire where up there in talent equal to Crane and the others.