Well, I found my Camry to be a well balanced car compared to a lot of other cars, underpowered yes, but easy to drive. You have a few swap options:
3sgte= 2.0 turbo from the MR2 and Celica awd turbo cars, has around 185 horsepower or so stock and some decent after market.
3vz-fe= 3.0 v6 thats easy to mod into the low 15 second 1/4 mile, even faster if you do a manual conversion. The 3vz-fe is also notoriously fond of boost, throw a nice t3/t4 turbo on there and it will love it, internals on a well cared for low mileage 3vz-fe are good for more power than the 3sgte, but you have to make the turbo kit yourself, luckily we have Toysrme and his 3vz guru skills :lol:
Id do this, fix your suspension first, im sure its pretty worn, get some nice coils or go with a good spring/strut combo to start with, that will tell you if you want to keep modding.
If you have money to spend, dont waste it on the 5sfe. Just save up for a 3vz-fe, a manual conversion or automatic if you really want to get into hardcore straight line speed. And some engine management (NOT an SAFC, go E-manage minimum but preferably something more advanced like the SMT series piggybacks OR go standalone (megasquirt).
you need to decide what kind of power you want before you really start.
Just post any further questions and we will help you out!