Are you talking 350 rear wheel hp, or at the flywheel? 350 flywheel hp probably isn't enough for 11s... To get close to that you'll need to gut the car completely, have slicks that hook like mad with steep gears (4.11s like you said), and be able to launch the hell outta that C4 (transbrake/high stall). You're gonna have to do some work to that suspension, too.
I've had a C4 in both of my '69s, I have a shift kit, a 2500 stall, and a tranny cooler. The car is just driven occasionally on weekends and cool nights when the weather is good. If I did it all over again, I would go with a T10 Toploader 4-spd in a heartbeat. It will be more streetable (especially with a big cam), funner to drive, and you don't have to worry about burning your tranny up because your converter stalls high.
If I was you I'd go with a carb, it would be easier since you wouldn't have to run any computer crap. Good heads, decent cam, good intake, 650 carb should get you 350 hp at the flywheel with a good tune. Definitely go with an electronic ignition (still haven't put one on mine yet
) and make sure your cooling system is in prime condition. Heat is your enemy!
Just a couple opinions and/or tips.....