It won't throw handling off too bad, it weighs about the same as an LT1... which many have swapped as well. Take a look at this guy's Cardomain:
http://www.cardomain.com/ride/641869
His LT1/T56 swap is what really inspired me. If you look on p12, you'll see that these weights are given:
1987 RX7 base: 2625lbs
1987 Turbo II model: 2840
His car ended up weighing in at 2820. Now given that all the weight is taken and removed from the same place, it won't noticably affect handling. Plus, with no A/C, no P/S, and more than likely a battery relocation to the back it should be close to stock.
Though in all honesty if I like the car enough, I will save my pennies for a nice heads/cam LS1.
It all depends on how much money I save over the summer and how expensive everything else is.
On top of that, coming from a formal Camaro-owner... I'm used to being nose-heavy and I'll just learn to control oversteer
