New spring install?

The hole will be welded this week-end.
When I bought the 72 Swinger. The guy gave me a 1970 B body 8 3/4 and these springs. Could it be that the springs are for a B-body? Are B-body springs shorter than A-body?
A guy at my local parts shop, suggested that I make a couple of spacer blocks and install in back of the shackle bracket.
So, how do I tell if these are SS springs?
Also, is there a left and right?