I didnt read this thread, but I highly doubt the stock arms have any form of HT, and if anything it would just be stress relieving, possibly normalizing.
What everybody seems to forget about long shocks isnt that the shafts are too long; its the body that is too long. You can have an 8" stroke shock with a 4 foot shaft if you want to, but when you start stuffing extra long shocks into the places and think, "well they will just compress and I will be OK," youre wrong. whats going to happen is the shock will be half way through it cycle, which means that other half is all youre gonna get.
Personally I think that 450 shocks on stock arms limit travel. The longer body doesnt permit the up-travel like you need to take full advantage of them. Whether you place the lower pivot further out on the arm or, the upper pivot higher on the frame makes little difference (in this case). Stock length shocks are the way to go.
About the lowering brackets, those raise the height of the upper mount, so you say cool. NO, if my bike was seeing any daylight under any tire I wouldnt trust those cheesy stamped alum brackets to hold my air filters, much less my life.