When Last I spoke with my friend he, He had packed up all of his reloading info as he was building a house and in the middle of a move. His stuff is in storage. He did indicate that you were definately on the right track by using a WSM action from the begining. When he built his, There weren't any Remington 700 WSM actions, there were RSAUM, but If i recall they were still hard to find. He used a Long action first, and had problems with feeding and couldn't ever get it to work, He later used this action for another interesting cartridge. (I had thought the current rifle was a Remington.)
He then found a short action, stainless Savage action. Opened up the magazine to feed the cartridges, then changed the bolthead and had Pac-nor chamber the bbl and install it. He then finished it with a Boyds Laminate stock which is bedded to the action. From this point he hasn't had any problems with feeding or malfunctions.
When he first began load development, he was using .300 WSM
cases and had to turn the necks. When Winchester came out with the .270 WSM, all he had to do was neck them down and fireform to straighten out the dents and achieve best accuracy.
I have no load data, but I hope this helps.