408 Cam on the way
That is a very small cam imo for a 408 with decent compression,the power range would be off idle to about 5k. If that's what you are looking for that's great but it is a big difference from what you had initially planned on. As far as timing chains I have used a bunch of the summit billet chains and the regular summit double rollers with great results, they all had good tension out of the box which can be spotty on allot of the chains out there.