FWIW - I've never seen a Cobra with too much camshaft. All of the streetability issues in normal (ie: heavy) street driven cars are not such a big deal with a Cobra. There are a couple of guys using Yates heads out here without a problem. They're in the 375 - 380 cube range, and they're running MUCH larger camshafts than what you've described. The light weight, combined with 3.5 or steeper rear gears, meant that any loss of low-rpm torque was never noticed. The overdrive 5th gear meant that cruising rpm is still fine with the steeper rear end gears...
While I do like the lower maintenance of hyd rollers, I wouldn't be concerned about wearing out valve springs with a large camshaft. There are still some pretty radical hydro roller profiles available. My solid roller camshaft was designed for pretty high spring pressure (240lb !), but every time I've had a rocker cover off the motor, I've checked the springs. They haven't lost any pressure since they were installed over 2 years ago. They've been through 2 complete engine dyno sessions, and I haven't been exactly kind to them while the engine's been in my car
