Front spring shackle bushes - reamer size

[Colin Wilks]

I am replacing the bushes and shackles on the front springs. The nominal dimensions of bush and pin is I reckon 7/16". Can anyone tell me if I am correct that I shall need two adjustable reamers, one at 13/32 to 7/16 and a second at 7/16 to 15/32 in order to size the bush? I'm assuming that once installed the internal diameter of the bush will reduce below 7/16". 

I'm off to the reamer shop first thing Monday for other stuff and don't want to splash out the extra £7 unless it's essential!