The #2 car in the second photo above (in a museum) appears as though it might have the Ford Indy V-8 from the mid-60s. I am not aware of any other V-8 engines that had the intake ports in the center of the top of the heads (intake stacks poking out at an angle to the side) and the exhaust ports in the center valley side of the heads where the intakes are on most "V" engines. I am not aware that there was ever a McLaren Indy entry. This is an interesting specimen.
A design description of the Ford Indy V-8 indicated that while the intake ports in the center of the head gave a very short, straight path to the intake valve, the exhaust ports exiting on the valley side of the heads compromised the exhaust runners somewhat and placed the headers in a very constricted space where achieving an equal, tuned length of free-flowing exhaust was made difficult. The compromises in the design proved not to yield an advantage, and this layout was not repeated.