road race engine...

If it is rallying, then it is some hours with RPM's frequently up to peak RPM. You're constantly going up and down in RPM and the gears, with the motor and drivetrain loaded and unloaded. It is not the severe loading that you will get in drag racing (where if you hook up with a lot of torque, then the whole drivetrain is under severe loading). So, due to the limited traction, you can back off on a lot of what you do for paved and drag racing.

If it is off road, in sand, like Baja, then it is a lot of time with the engine and drivetrain heavily loaded. Trannies and gear oils take a lot of abuse whenever you get into sand.

For rallies, the A body front suspension is actually decent, just limited in travel. Longer T-bars is the answer to that Like from a C-body).

The rear live axle and leaf springs needs a complete overhaul and change for rally use; it just doesn't work well at all in rough stuff. The bump steer is bad, the axle is heavier than needed for the power you can put down, and the leaf springs have a naturally progressive rate which makes matching the spring rate and shock rate badly compromised. And again the travel is limited. Something like a stout but light rear axle (like a Toyota /U rear axle) with coil-overs, and a 4 parallel link with panhard rod setup was the best live axle rear setup ever derived for rally use.