1. if a gsr crank is used, gsr rods have to be used also to compliment the stoke of the gsr crank.

2. if u wanted to use a gsr main girdle it would have to be machined to fit the ls block correctly and the main bearings would have to be sized and measured because the letters on the block and numbers on the crank would mean nothing since the block mains were altered. also all b series main bearings are the same.

3. ls head gasket

4. the block is not altered in any way except youll have to find an oil source for the vtec supply for the head. most people "T" off the oil pressure sending unit hole in the back of the block, but some companies now make oil filter adapters with fittings coming out of it for either vtec supply, turbo oil feed, oil press. gauge, etc.
the only thing that is tapped and plugged is the factory vtec supply passage on the bottom side of the head (its back corner near the dist). a 1/8"npt allen key plug is used after its tapped. and i would recommend the dowel pin adapters to relocate the dowels to that back side of the block instead of drilling them out. i believe golden eagle makes them and they cost like 20 bucks.

5. gsr headstuds would have to used, not LS because the 2 center headstuds are longer for the LS

hope that helps