Custom pistons tend to be pretty pricey, and the tool steel rods from Carillo, Pankl, etc. are over the moon! There are several sellers on Ebay that recycle slightly-used engine parts from NASCAR race teams. Those parts are generally around 10% of their original cost- - - -a set of $2K rods for $200.00 or so. They use a very small rod journal, which allows a crankshaft to be reground way off its original centerline, increasing the stroke. Flathead Ford hotrodders were doing the same thing 60 years ago, using 85 HP engine rods to increase the stroke of the 4" Mercury crankshafts to 4 1/8", or even 4 1/4" by doing a little welding on the rod journals. We made 3 9/16" strokers for 350 Chevy engines the same way- - - -using 2" diameter rods for 283 engines and grinding the 2.100" crank journals a little off-center. The rods I'm looking at are 6.450" long, with a 1.850" crank diameter. That allows the stroke to be increased from 3 15/16" to 4 3/8" by offset-grinding the center of the stovebolt crank journal, and creating a shoulder that keeps the narrow rod centered, like the "Cadillac" stroker does with the 292 rods. It would take some creative machining, but that long stroke should make ridiculous amounts of torque. Increasing the old flathead's stroke by 3/8" made then torque monsters, especially when running 11:1 compression on alcohol!
Jerry
