I've only tried the one car I selected....the Elf Martini Mk19, but I'm a bit confused by what's available in the setup menu and what some of the limits are for adjustment, especially in the powertain area.
In the Differential area, the lowest you can set the Coast and Power settings to is 60% or so, yet you can go all the way up to well over 100%. There's also a lot of built in Preload as well that will only go so low. There's no RPM setting adjustment...the engines might have been rev-limited, I don't know if they were but I don't think the FIA did that in 1976, especially considering they opened the field up for race-built purpose engines...which is what brought Renault and Hart into F2 in 1976.
Anyone have any information on what all the FIA ran, rules wise, in 1976?
Yes, the drivetrain values look pretty odd, Steve. But you can work with it

Regarding rpm - very true, there is no adjustment possible.
I suppose I've been the one here who did the most laps in F2, as I did a complete offline championship in January and February, as close to the historic F2 championship as possible.
I couldn't find anything regarding rev-limitations of the engines in F2 1976. Only the information you already got, that pure racing engines were allowed. Regardless of the non-existing RPM setting adjustment - in the entire series I did not have one engine failure, while driving a March762-BMW.
It was close at Enna-Pergusa, as I could only find the old layout which was almost all the time flat-out and I had to lift throttle later on in order to cool down the engine, which was overheating. This happened with the radiators already opened to the limit. The AI did not do this and many cars had broken engines in the end. With the tracks we use in this mini-series there won't be such a problem. The engine can get hot at Hockenheim for sure, but it lasted 40 laps several times wothout any problems. Anyway...It is imo crucial to have the engine cooling set up properly.
The LE car is also based on the March762-BMW for the sole reason, that it's very reliable and has good enough power. I wasn't so sure about other cars, most certainly not the Wheatcroft, which always suffers engine failure after a few miles. That is afaik not a bug in the mod, this is by design.