[Racer-X-]

You have the heads from an L31 vortec 5700? Or some other "vortec heads"?

With stock springs and valve train parts, the stock L31 heads are limited to somewhere between 0.460" and 0.480" total lift. It varies with the castings and parts and must be measured. The first cam might work with stock valve springs. The second one will at a minimum require alternate "beehive" valve springs. And if the coils bind on the stock springs with the first cam, it will also need these alternate springs.

If it's mainly a street driven vehicle, the first cam is probably going to be a better choice. If you're going to run it down the drag strip more than a few times, the second will make more power, but may not be as good at lower RPMs. You'll probably want a higher stall speed for the torque converter with the second cam.

 

[Racer-X-]

With that gearing and transmission, I think cam #1 is the one to go with.

I would still recommend putting a "towing" type ~1800-2000 RPM stall speed torque converter in while you're installing the engine. That will help some with your gearing and work better with that engine.

And for the Vortec heads, are you going with junk yard heads? Or buying new ones from somewhere?

If you're buying new, check the cc's on the combustion chambers. They should be 64cc +/-. Use a 0.028"-0.030" compressed thickness gasket with new heads.

If you're buying used heads, this is pretty important. You'll probably want them milled flat. Mill them to 62cc chamber volume, and install them with a 0.040"-0.043" compressed thickness for the head gasket. This keeps the floor of the intake manifold runner flat with the floor of the intake port on the head. If you get any kind of "step" there, you lose HP and Torque in a hurry.

If you want to mill for more compression, you absolutely have to mill the sides of the heads or the side faces of the intake and the bottom of the intake or the walls of the block valley by corresponding amounts (this is complicated because of the angles). If you do it right, you can mill for added compression. If you end up with any kind of "step" in the floor of the runners and ports, even as little as 0.010" at the junction between the head and intake manifold, you'll be losing power and torque.

This is a detail that most folks overlook, but with the Vortec heads, all the magical flow properties at moderate valve lift come from the floor of the ports, and any turbulence there from any kind of mismatch hurts performance and fuel economy.

 

[Racer-X-]

These are factory heads on a 350 I have that needs rebuilding. So they will need to be worked

Then it's 62cc chambers (typically mill 0.011"-0.012" from the head surface) and use a 0.040" (ish) compressed gasket, which is far and away the most common thickness available for that engine.

Valve job is a good idea, obviously. Unless the machinist is volunteering a week on the flow bench for free, don't let them do anything to the ports past the valve seats. Those head with stock ports will work just fine with cam #1.