If I put all internals of a gsr plus head in b18a1, wouldn't it be a gsr?

 

nope.
Cranks are different, b18c has oil squirters and a block girdle, among other things.

 

The block casting is different, namely the passages for the mentioned oil squirters and an internal VTEC oil supply for the head. The oil pan, windage tray and oil pickup is different to accomidate the crank girdle, which also doesn't directly bolt to the -A block (but will with modification.) The -A block also does not accomidate a knock sensor.

 

pistons are about the only thing that will work in a ls block to bump up that compression alittle bit other then that.. rod stroke is too short and the crank case are completely different.

 

If he used the GSR crank, it would be fine to use the GSR rods. I always thought the windage tray/pickup would go onto the LS block no problem? Z10 used to sell a block girdle kit for the LS/B20 which came with a GSR windage tray and pickup...and as far as I know, required no modification to fit.