1999 Boxster 2.5 - 996 3.6 Upgrade

Vehicle Information: Year: 1999; Engine (type, size, modifications): 2.5L; Total Mileage: 73000; Transmission: Manual;

I've been investigating ways to get more power. Although the TPC supercharger is enticing, I'm afraid it will tax my 73k-mi engine too much. Would you agree that an engine replacement would be a better idea?If so, can a 996 3.6 be fitted? I've read about 3.4s, but not about 3.6s. What should I look out for? Please give any advice you think of.Thanks.