Using LS Rods in a D series:

The crank ends of the LS rods and D series are same size around at 1.890″ (48mm). The crank end bore width needs to be milled to match the D16 crank rod journals. Shave .022″ off each side of the crank end of the rod.
The piston end bore needs to be bushed to match the D16 piston’s smaller pin size. The pin on the LS pistons is 0.826″ (21mm), the pin on the D16 pistons is 0.748″ (19mm). You need the custom made aluminum-bronze bushing with a width of 0.786, ID. 0.748, OD. 0.827 +(over) three thousands due to the bushing will be pressed in the small-end of the LS rods, so the bushing won’t come out of the hole. Crower sells these for around $40 a set.