You sound like you want to do the swap already. If you dont want your GSR motor though, I'll take it off your hands.

Basically, what everyone is gonna say is, yes, the B20 will probably yeild a high hp and tq rating in the end. Thats after thousands and thousands invested. With the GSR engine there still is a lot of potential and at a much cheaper price. If you've got money to burn, go for the B20, reliability shouldnt be as big an issue if you can afford it. If you are working on a more limited budget, or want to keep the cost low, keep the GSR. They're reliable and do respond well to turbo, despite vtec. It's a more simple project and will yeild probably the most hp per dollar invested. But, as I said earlier, if you want the best of the best, go for B20, just be prepared to invest a small fortune in your car.