easy to do if you just use an LS crankshaft and LS rods. make sure you use LS rod bearings also. The pistons fit a little different from the LS and GSR, so you will either need to machine the small end of the ls rods, or the rod clearance on the GSR pistons. Also, the piston oil squirters will need to be bent slightly to clear the LS crankshaft counterweights.
- Best of luck!