Rods and pistons are easily available. 5.7" small journal rods (2.00" crank journals) from any 283 or 327 SBC up to '67 will work. Scat makes a small journal rod in their Pro Stock series, part #2570020P for a pressed pin rod with 3/8" ARP cap screws
, part #2570020 for a bushed pin with 3/8" ARP cap screws
. Eagle makes rods in their SIR series, #SIR5700SBLW
for bushed pins, #SIR5700SPLW
for pressed pins. Both companies also make stronger H beam style rods (for more $$$$ of course).
KB makes 2 hypereutectic pistons for the 283, KB165 is a flat top 2 valve relief piston
with a 6cc dome volume, available in .030", .040", and .060" overbore sizes (no stock bore listed). KB166 is a domed piston
with -4cc dome volume (available in the same overbore sizes as the KB165). Both have a 1.805" compression height. With a 3" stroke and 5.7" rods these pistons will give a 9.005" stack height, in a stock 9.025" deck height block the pistons will be .020" in the hole.