My brother is currently doing the same with the same receivers by gathering parts. He is waiting for a krieger barrel in 6.5cm.
I guess as a outside observer, the biggest thing i noticed was that his cost for parts/build climbed higher and faster than expected. Simply because thought was always, "Well heck I got a high end, fancy receiver. I might was well pay a little extra and get the fancier (insert other part)." I just that was funny since it wasn't my moneys.