I have the ruffstuff housing and a currie HP center section with gears sitting in my garage, and both were screaming deals. I just bought a set of shafts off here, all I need is the inner/outer knuckles and hubs now and I'll be set.
I don't know what your saying about the coil mount? The 78-79 style HP60 is the best in regards to having the longer drivers side axle tube, but it doesn't matter considering the ruffstuff housing is all steel so I can weld anywhere.
I personally think the only way to build a 609 is to match some stock length, so you can get used stock shafts or off the shelf upgrades instead of having to get customs every time you break something. I picked up a stock set for now because I can't imagine I'll have problems with 36"s.
*edit for bling factor haha*