Long story short, I had these made for one of my cylinder head customers but then he got a cancer diagnosis and had to bail on the project. I kept them for another project for a local friend of mine, but after waiting over a year for a BBM block he finally bailed on that and got a Pond aluminum block. The Pond aluminum blocks won't go this big on the bore, so these pistons are now available. They will work on any aftermarket iron block, or a Shelby big bore aluminum block. They are too big for a factory iron or Pond aluminum block. They will also work with any FE cylinder head, including the FE Power heads. A picture of the spec sheet is attached, but basically they are for a 4.25" stroke, 6.700" BBC rod with 0.990" pins, are 11:1 compression, and use 0.9mm steel top ring, 0.9mm Napier second, and 3mm standard tension oil ring. The pistons, pins, and rings are included.
My customer originally paid >$1500 for these parts; selling them for $1050 or best offer.