Pistons Problems

Can anyone help me figure out where i can find pistons for my 68 pontiac 400ci i need pistons to fit a 4.15 bore and a 4.25 stroke i cant find them anywhere the only place i can think of is custom ross pistons but was in hope that someone knows something i dont thanks.

summit normally has everything...

here's the only one I found: http://store.summitracing.com/partdetail.asp?part=TRW%2DL2323F30&autoview=sku

if you click thru the departments and parts by category it should take you to this page that shows it works with a 4.25in stroke. the parts spec page doesnt explicitly say it...
http://store.summitracing.com/egnsearch.asp?N=700+4294925232+4294839001+42948910 96+4294791059+115+4294774647

if you want something other than the dish piston that one is (to change compression ratio), I would try looking thru the catalogs at Napa or Autozone