my friend had his b16 head on a gsr block in his crx and it was pretty quick. he had type r cams, valvetrain, CTR pistons, his head was milled, skunk 2 cam gears.
ls/vtec is also pretty good although I still think vtec heads belong on the blocks they come with.
you can probably expect higher whp and torque #'s with the ls/vtec setup depending on your plans for the motor. FI or n/a.
so bottom line is your choice, you can probably get an ls block the same price if not cheaper than a gsr block, depends on whose sellin it I guess, but you can check on thepartstrader.com.