First off, the WSM family uses the large shank barrel. You will need a large shank receiver. Then, you will need a longer firing pin assembly (the standard short action firing pin is about 0.50 short) to make use of the standard WSM bolt head.
I have successfully used the standard magnum bolt head in my WSM conversion, however, I take the risk associated with it. And apparently Savage started out using the mag bolt head until some folks were complaining of potential or actual bolt head failures due to the increased pressure associated with WSMs. All I can say is I have loaded within the load map and so far see no issues with using the mag bolt head. If you load hot then you may find out why the engineers went to a heavier head.
In addition, the WSM bolt head uses an ejector which is action mounted. So this is why I went to the original magnum bolt head to work around the ejection issue.
Finally, the WSM bolt head is a controlled round feed which was supposed to improve feeding. I have not come across a failure to feed with the standard magnum head.
As for magazines, all you need is a short action WSM mag. I converted a normal short action by opening up the feed lips a lot to accommodate the larger diameter cartridges for which took some time. Doable, but in hind sight would recommend to just buy a WSM mag and be done with it.
If you are not comfortable with such tinkering then I would steer you away from the notion and suggest you go out and buy a WSM rifle to start with and not play with such things. It is not for the faint of heart or for those without the understanding of the details.
My 2c
