Jegs has those FHR pistons for the small blocks...
United Engine Machine IC9975.040: Chrysler 340ci FHR Forged Pistons Flat Top 2V | JEGS
I believe you are looking for 4.080
https://www.uempistons.com/catalogs/icon_catalog.pdf
on page 68 of catalog......piston weight 606 pin weight 118 grams