I have 400 hp (416 tq) to the rear wheels (dyno'ed) in a 2660 lb car (driver & gas). I love it.
Feels like I can pass anything up to a jet.
I have buddies with big blocks, 600 - 620 (619 - 657 tq) at the flywheel ( dyno'd) that let me drive their Cobras. I think they are a little heavier than mine. Both pull like a train after 80 mph. I drove one 50 mph to 140, very fast, felt like it would do 200.
In my opinion 500 rear wheel is a useable number. You can hook up with good tires and control the Cobra.
Dwight