[Excaliber]

The original Ford book I have lists it as 4.233, my block is .017 over bore, a typical size. 4.250 results. .017 is SO standard you can buy "standard oversize" pistons in a 4.250 size.

But those "stock" oversize pistons may not work just because the "bore" is correct. The "compression height" (piston pin location) also has to be compatible with the engine block deck height. And LOTS of blocks HAVE been decked over the years!

Mine was, so I was forced to order custom pistons for my "stock" .017 over bore to get the right piston height at TDC.

Stroke was the same for 390, 391 Truck, 406 and 427 at 3.78"

410 and 428 went to 3.98"