Future LS Build Advice Needed

[DreamRyder1963]

I have decided that I am going to build a LS engine for my V8 Corvair build. The car will be sitting on a G-Body chassis; it will most likely be from a '84ish Monte Carlo SS. My goal is to make 400-500 hp naturally aspirated without spending more than $3500-$4000 on the engine. I have not decided which LS I will be using, but it is likely going to be a 5.3l due to the cost and aviability. I have heard that it would only take a good cam swap to make these numbers but I would like to known for sure. Any help or advice would be appricated.