what cam for my 5.0?

VERY broad question, it all depends on what your application is. Is this a street car? Race car? Where do you want the power to be? Low end torque? High rpms? NA motor, blower? In order to get a detailed answer, give a detailed question so we know where you are coming from, and where you want to be with this motor. There are thousands of cams available. With that being said, you will never go wrong with contacting Ed Curtis for one of his custom cams. He's one of the best in the biz, and all you have to do is tell him what your goals are, and he'll do the rest. Good luck, and welcome!!!!

are the heads ported? what size is the motor?

even to a 347 you are still going to have to spin the motor higher than the basic 6000rpm to take full advantage of the manifold . . . meaning your valve springs probably aren't going to cut it.

talk to any of the custom guys and tell them your plans. There are some good hydraulic designs out for something like your setup (like from AFM) but this needs some good timing events to make work unlike the bolt-on junk which is like 90% of the cam threads.

you probably would be best served by reading quite a bit more . . .

The Sr heads have 2.02 and 1.6s which is quite a bit bigger than the stock valve reliefs. You definitely need to have a better plan as the intake will not suit a cam than is so mild that the events will not interfere with the piston.