(This is a modification by John Titus)
Closed Coolant Recovery System
Replace the thermostat housing at the back of the engine with a Moroso 63420 Manifold filler neck kit (available at most speed shops or on-line for about $50). This places a radiator cap on the engine so you can still fill the cooling system once the tank is gone. Use M7 x 80mm bolts to mount it.
The filler neck kit has three pipe fittings on it. I put a Chevy overtemp sender in the large one (1974-78 Chevy Blazer or GM Pickup - Standard TS43; Wells 1T1059 or equivalent), I plugged one of the small ones with a 1/8 inch square head pipe plug, which I had cross drilled to hold the throttle return spring. I put 1/8 inch 90 degree hose nipple in the other small hole. I also added a couple of M5 holes to mount the choke cable.
Next, I ran a piece of vacuum hose from the nipple on the water neck to the air bleed nipple on the radiator. Later I replaced the long vacuum hose with a piece of 3/16 (4mm) nylon tubing and used vacuum tubing at the joints.
Finally, I plugged the extra outlet on the water pump cover (by tapping inside of the cover for a 1/4" pipe plug).
With the coolant tank gone, I can get to the fuses and general accessibility is greatly improved.
The coolant overflow tank can be put anywhere (I originally put it next to the oil cooler, but later moved it to the smog pump bracket for easier access, then finally made a small bracket to hold it where the header tank used to be - the plastic tank easily lifts away to provide access to the fuses).