Should i buy a new shock, it would be a Revox. Manitou makes awesome shocks and their customer service is top notch... I know where i'm staying... XD Actually rode a Revox last week as well. Was just awesome and the damping was far nicer then anything i've ridden. Blows the DHX out of the water...I think the best way is to buy a Fox.
I also tried building it at first putting it together without changing anytihng except using 2.5wt KYB shock oil. It did the top outs also. I took it apart again and used 5wt this time but also took out the spv valve outter ring and used shims. I did not cover it totally but it's pretty well covered. I used the instructions of here and took shims off an old Sherman damper... It looks like the pic below...You've got to make sure that the compression holes on the piston are blocked off when it's rebounding or the oil will blow right through them causing top out. If the shims you put in there are too small diameter or they aren't against the piston/valve those holes will be open.
http://www.mtbshock.com/swinger_5th_shim_mod.htm