Chain Boxes and Covers

[B D]

I am trying to put things back to the way they were so I am removing the carrera tensioner and going back to the spring tensioner with safety collars. The question I have is about the chain boxes and covers, I know I will need new covers but what about the box I remember hearing the studs are different on some boxes?

Here's what I have:
Boxes- 901 105 101, 102
Covers- 930 105 105, 106
Tensioner- 930 105 547
(soon to be for sale)

And what I will need possibly need:
Boxes- 901 105 061, 062
Cover- 930 105 063 (Left), 901 105 064 or 930 105 064
Tensioner- 901 105 050, 930 105 053, etc...

So what do I really need? Do I need diffent boxes are the part numbers correct? Also what about magnesium vs aluminum boxes and covers could an aluminum case have mag boxes from the factory?

[B D]

Early boxes, 1967 and earlier, have 7 studs and later boxes 68+ have 11 studs. I guess I can just get new covers and keep the boxes if need be. I think I may have figured this out.