My first 5.0 build up

The thing I'd be most concerned about is putting together a package that makes good low and mid range torque. The Thunderbird is significantly heavier than the Stang, and having some grunt on the bottom is gonna be important. Your blower selection should help with that - but I'd reconsider your cam choice. There are better alternatives than the E for low rpm torque and blower compatibility. I'd contact CompCams and work with their tech folks on a choice, or contact one of the custom grinders on the sites - Buddy or Ed. For the money you're putting into it, it's only a few dollars more to have your set up modeled by someone that can help assure you that the package you put together is gonna perform the way you want it to.

You may want to rethink your head choice if you're serious about those power/torque levels. Also, I'd think about something other than the stock block - you're in the range where it's not uncommon for stock blocks to split.

There are people that make stronger blocks - but building a serious 500-600HP/ft-lb 302 and "budget" don't exactly go together. Do some searching around - Dart makes a block, I believe Ford Racing also makes a stronger-than-stock block; there are probably others.

A girdle won't solve the problem, although it may delay things. Don't get me wrong - there are folks out there getting that much power from supercharged or turbo'd 302's - but it's not uncommon to read a thread which is titled something like "I split my block! Pics inside...." -- the pics are usually pretty spectacular.

The fact is, a good quality short block with compression for the supercharger, and a modest amount of boost can get you a reasonably reliable 400HP/ft-lbs and you shouldn't have to worry about breaking things if your tune is right. And that should move the T'bird along right smartly. Just remember - keep the blower a positive displacement type so you've got plenty of grunt down low, and have a custom cam designer work with you on component selection so you don't end up with a cam that's not the best for what you're trying to achieve.

You might try another post aimed at getting the supercharged crowd to share their set-ups and HP/Torque figures with you. In it you can ask them about stronger blocks and such.

I've heard dart blocks are good, but they're also high for a new one 1500-2000 new for the block alone if I remember correctly. Ford Racing does make a stronger-than-stock block, it's called a Sportsman block and I believe it's around $800 new. I've also heard that the "Mexican" blocks are stronger than the one's stock in the stangs. My guess would be the Mexican blocks came from 302's sent to Mexico, but not sure why they'd be stronger. Search for "mexican block," and you should come up with some results, but not so sure i'd use one for a 500-600 lb/ft torque, 400-500 hp car.