I think Gen3 is far and away the best option, given your power goals. I haven't had mine dyno'd yet, but there are a lot of folks that don't believe me when I tell them it only has 245ps. (I.e. Mustang Cobra and Pontiac GTO drivers.)
The only parts concern is if you need something that isn't in stock. It could take 3-4 weeks to get. Most of the stuff that isn't available is engine internal and other major stuff that is going to leave you stranded. Mine isn't a daily driver and I don't have an active race campaign, so this is no concern for me.
If you are handy and do all of your own work, you'll have no problems. There are a lot of resources for tech info, the BGB is still good for everything but the drivetrain and ECM, and there are wiring diagrams available for those online.
No worries. Get a good clip and you wont be disappointed. Champion generally stocks tune-up parts, t-belts, t-stats, etc. Most of the routine stuff you'll need unless you're f'd in the a anyway.