Hello Geof,
First of all, welcome to SGW.
For what you are trying to do, I would recommend our new 20/28(R) powder. We have the exact loads you describe documented at the attached location.
http://www.alliantpowder.com/products/20_28.htm
Our Unique(R) will work very well in most cases, but it is the WinAA case with the AA20 wad combination that will frustrate you. That wad is very tall, and that makes the loads with a bulky powder such as Unique really tight with that combo. The wad pressure required to make loads such as those bring the chamber pressure up very rapidly, so we recommend only 13.8gr of Unique in the combo you seek. That tested 11,200psi, so it may possibly be brought up further, but we don't recommend any higher.
Please consider buying 20/28, I am sure you will be very pleased with its performance. You will need to find a bushing that throws between 16.0 and 16.5gr, and this will work for you in all the combinations you listed (be aware the Estate hull is the same as Federal, if it has a brown paper basewad). The performance in each hull will not be the same, as the velocities in the Win and Rem loads will be 40-50ft/sec higher due to their designs, but they will all shoot fine at moderate pressures. I am not exactly sure which bushing will get you there, but I will tell you that while I was developing 20/28 I had to build up the G bushing with tape to get 15.5gr, which was what I was loading. That was the smallest bushing I had before I purchased some Hornady bushings to get what I wanted. I ended up using the 354 bushing to get 15.4gr. I think the G may be close to what you want.
Please feel free to contact us at 800/276-9337 during business hours and Ben will help you develop loads. (Our offices are currently closed until Jan 2 though.)
Good luck with your project, it sounds like fun.
Shoot well,
Paul