The rods on the 4G61 are exactly the same as the 4G63 rods. So basically the choice of rods is endless as just about every man and his dog is producing them.
Pistons are a different matter. Im using hyper-eutectic cast alloy pistons although they were originally cast as stock compression N/A pistons which means they were domed at 9.2:1 compression. The pistons had the domes machined off to create a flat-top piston with CR of ~8.7:1. The crowns were then ceramic coated and moly-disulphide coated side-skirts. The heat treating necessary for the coatings also re-normalises the piston to relieve the stress induced from machining.
Given that the 4G6x blocks are supposedly taken from the same castings, you should be able to bore the shorter 4G61 block out from 82.3mm to the 85mm of the 4G63 and just use some forged flat-top pistons designed for that motor. hmm, a 1.7L big bore 4G61 I wonder if that would work. You might even get a 'stroker' motor out to 1.8L.
