Wow, everyone is pretty free and open with someone else’s money. Having done so many similar type swaps and modifications, I would not ever touch one again. Here is why.
An LS3 costs about $7,000, then you need either a kit or need to be good with a welder to make engine mounts, frame brackets, modify both the cross member and transmission cross member, let’s not forget the LS3 is a computer fuel injected engine and doesn’t come with wiring harness or ECU – add about another grand. Custom headers and exhaust, add power steering and power brakes and likely disc. Drive shaft will need to be modified for 500 horsepower, front end will need to be modified for the heavier engine, so new springs and more. New radiator for the new engine. New differential for the 500 hp engine. New or rebuilt trans for the 500 hp along with a trans cooler. Likely new dash and gauges. What will this give you? Assuming you do all the labor yourself (hundreds of hours), you will likely have about $20,000 of just parts in the car, not counting the car or labor. When you add in the $15,000 car shell, you have a $35,000 car (not counting labor). This does not include: safety belts, collapsible steering column, air bags, interior, air conditioning, paint and more. Is this a car you would want to drive to work every day? Probably not. Would you want the wife driving this to the grocery store a few times a week? Probably not. Would you want to drive this in the winter when the streets are slushy or icy? Probably not. Would you want to drive this in the heat of summer (without A/C)? Probably not. So you will have a $35,000 plus vehicle in your garage (depending on where you live) 8 or 9 months out of the year. A vehicle that would not be safe or protect you for speeds above 40 mile per hour (since it will not have safety equipment). Most vehicles of this era tend to twist (both body and chassis) when subjected to 500 hp or more, unless major body and chassis modifications are done. Yes, you could add safety equipment and such for about another $5 thousand. You could also spend about $5 to $10 in body and chassis modifications to make it strong enough for 500 hp. Will this car really be worth $50 grand (not counting labor)?
To me, this sounds ridiculous in having this race car that is not safe and cannot be a daily driver or be driven year round. I would prefer a new Mustang or Camaro that is safe, can be driven every day of the year, and would be able to out run, out stop, outperform, and out maneuver just about anything. Lets also not forget about insurance. Your insurance agent will have a heyday quoting a 500hp home made vehicle.
Would you be able to get your money back out of this vehicle should you decide to sell it? Unlikely.