You have the older ATE brake caliper. This is a "single acting" caliper (it only has one piston). One piston means that the caliper must physically move to allow BOTH brake pads to apply pressure to both sides of the brake disk equally. This is why the caliper pivots. Physically adjusting the eccentric screw on the caliper housing is also required because a "single acting" caliper cannot "self center" on the rotor. 

1) Check that the front wheel rotates freely before the caliper is mounted.

2) Lubricate the eccentric pivot bolt with water-proof grease before installing.

3) Lubricate all the piston parts (seals AND piston) with DOT4 before assembling. DO NOT introduce ANY type of "grease" onto any internal brake fluid areas.

4) Use a C-clamp to make sure the caliper piston is all the way collapsed into the caliper before mounting.

5) Check the position of the new brake pads.

6) Mount the caliper using the freshly lubricated eccentric bolt.

7) Intermittently spin the front wheel and apply the front brakes while adjusting the caliper position. Try different eccentric settings. 

You will eventually find a place where the front wheel is able to spin (maybe not "freely") but with less resistance. Step 7 needs to be repeated several times over the course of the next few months.

NOTE 1: You should also take this opportunity to install steel reinforced flexible brake hoses to double your stopping power. See THIS article.

NOTE 2: You might want to investigate the purchase o a EBC floating brake rotor. With the rigid OEM rotors, the caliper MUST be adjusted correctly in order to allow the caliper/rotor pair to center. The "floating rotor" adds a second place for movement and therefore allows much easier adjustment and self centering. Secondly, the alloy of the rotor also offers a much, much higher level of stopping performance. 

LOL = What a BFO I had.. After I reread your list.. I had done All of the items 1 thru 6, and Tried to spin the wheel when it stuck after a partial spin!  I couldn't move it or the Bearing pin.. cuz I had removed the Helper Bolt (!?)  So this afternoon I put the Bolt back in, Turned the Bolt with my Set-screw wrench a half turn and that freed up the wheel so NOW it turns freely!  [& don't I feel like an old fart!]  The Clymer Manuals & Brooks say Nothing about manipulating the Bearing Pin "Eccentricitiness"  to free up the wheel. [& I did sort of jam it up in there. lol]  I did find a eccentricity reference in a video about drawing lines on the Brake Disc itself then rotating it to check for proper wear patterns, for LATER.. But I have yet to Replace the Brake Line with a new SS Line, RE-FILL up the Master Cylinder with DOT-4 Brake Fluid .. and Bleed the Front Brake system.. [I replace the Master 5 years ago. Hope its still good, looks okay, no leaks]

Thanks RICHARD W for the List and Hints!!  

Some more thoughts...

1) Sometimes inserting fluid from the caliper-end of the system is easier than from the top. This is because air within the system wants to naturally rise. So having the fluid level rise is far more natural than forcing air out the bottom. 

2) The system will tend to "self-bleed" with all the air bubbles escaping into the brake fluid reservoir while the FB lever is slowly pumped. However, having the master cylinder (M/C) canted at the angle of the frame tends to trap one last bit of air. If you have a motorcycle lift you can raise the rear wheel until the backbone frame tube is horizontal and that will help "bleed out" the last bit of air. 

3) The under-tank M/C had to be used because the Gen 2 handlebar-mounted M/C hadn't been invented when this system was introduced. However, over time the Gen 1 location has proven to be a liability in ways that were never considered. One of the big ones is that any leaks from the Gen 1 M/C has the caustic DOT4 brake fluid dripping directly onto a critical part of the electrical system, especially when using the side stand. This then corrodes the brass terminals of the Starter Relay which can stop not only the electric starter, but also the entire electrical system. Highly suggest you read THIS article.

(The handlebar mounted M/C is far superior for many reasons and if you ever have the chance to swap the Gen 1 M/C for the Gen 2 bar-mounted one you should do it. The 2 parts of the system can then be connected together using a custom made flexible brake hose available from several makers, such as Fragola.) 

Hope this helps