$1300 for a 45+ hp jump isnt bad at all. Plus it gives you a great platform to build upon. Power to weight isnt a big issue at all. The motor only weighs 30lbs more, and after removing AC and power steering, youll be less than the stock motor anyway.
00IntegraLS, a GSR swap goes for around $2200-2600 on forums for a USDM engine, with 70k. A JDM from Hmotors i can only assume is more. I was very lucky in my search, and got a B18C1 longblock for $1000 with 70k original, and 0 on new pistons and rings. I got my tranny for $600 with 9k miles, and my ECU for $65. $1665 for a GSR swap is VERY cheap.