there's tons of factors to weigh in this. both are easily capable of putting down 200+ with about 3k worth of parts.
A basic turbo kit is 3k, and should put the ls right around 200
going all motor is expensive- cams, headwork, and so on add up fast, and offer minimal gains per part...
on both though, you're going to want to improve other aspects of the car beside the power adders- intake, exhaust, header if all motor, and wheels tires and suspension should NOT be overlooked.
a GSR will cost more than a comparable LS intial cost of car
a GSR will cost more to insure each month
you mention track- if you mean drag, I say go LS. if you mean road course or autox, go with the gsr and go NA. a lot of leagues don't allow turbo cars, and autox will put you in a stupid impossible class with a turbo car
If i had to choose, i'd get the LS, boost it... and later on down the road if i wasn't satisfied- i could upgrade internals, run more boost, run better fuel management and do a vtec head swap if i wanted.
with the gsr, once you go high compression pistons and all motor cams, you're pretty much at your limit- before you go into totally re-doing the block.