I'll guess you are putting these brakes on a pre 73 A-body, retaining the earlier K member. If that's correct you probably should place the left spindle on the right side and right spindle on the left side so calipers go to rear of spindle center ( like 1 o'clock position instead of their original 11 o'clock position ). That first pic shown above is what you would want end up with. Look closely and you can see how the caliper would hit the stabilizer bar had it been placed at forward position ( like they were in those 73 up assemblies ).
Even if you don't have a the stabilizer bar and that conflict today, you might want to add a stabilizer bar later on. There are other ways to work around this swaybar caliper conflict but the most common method is stated and shown, switch the parts left and right. Buy the slightly longer F-body fluid hoses. A-body hoses will bee to short for this assembly method.
The only snafu that some run into is when a bearing destroys a spindle. They'll start searching for a left side spindle when they actually need a right spindle for their left side.