I'm about to put my 1200 motor back together after repalcing the bearings and honing the pots...one of my books mentioned that you should not reuse the piston pin circlips. Is this true?? Is it possible to buy a set of circlips??

Buy em, cheap as. Its just not worth putting used clips back in, they lose their spring once taken out and if one pops out with the engine running there will be hell to pay.
For such a seemingly insignificant part they will do a lot of damage.