Well, I have a book called the Camaro Restoration Handbook that has been pretty helpful. Probably not THE most detailed, but it is good and gives some helpful tips.
As far as the fuel tank goes, it isn't too hard actually, at least on my '68 it wasn't. I know that the '69 has a slightly different tank that has the filler neck completely connected rather than being in two pieces.
For my '68, I first unhooked the battery. Then, I disconnected the fuel tank sending unit ground wire (screws to the underside of trunk on the tank reinforcement strap just in front of fuel tank). You will also have to disconnect the actual sending wire from the wire harness. This is a little clip in connector that must be pulled out of the harness... it connects right in the middle back of the trunk, just behind the filler neck.
After these wires are out of the way, I took off the filler neck shield and took off the gas cap. Behind the gas cap (on the '68) are 4 screws that hold the filler neck to the tail panel. Unscrew these. The next step on the '68 is to pull out the top part of the filler neck, which is possible by loosening the rubber connector hose, accessible behind the liscense plate. Because of your one-piece filler neck, this probably isn't necessary... and I am not sure exactly how difficult this will make removing the tank.
Then, I removed the rubber sleeve from the trunk. This goes around the filler neck which was just removed.
Now, get under the car... Begin by unhooking the rubber connector hose from the tank fuel line to the front to rear fuel line. This ensures you won't bend anything. Then, start at the rear of the tank, unscrewing the long bolts that fit into the frame. After these bolts are out, the tank straps can be pulled down so that you have access to the screws that hold the front of the straps on. While supporting the tank, unscrew these. Once the screws are removed from the front part of the straps, the straps can be slid forward, removing them from the underside of the car.
Your tank is now free. Because of your filler neck though, you will probably have to pull the tank forward (towards the front of the car) while lowering, to ensure that the neck comes out from inside the trunk. That should be about it...
I did all of this with the rear suspension removed, which makes the job much easier I would imagine. No differential to get in the way.
I can't tell you about the heater core yet... but hopefully after this summer I can!
That is the next job...