To Stroke, or not to Stroke

If you can do the installations yourself, $14K is a doable budget for a 451 car from a /6 car. A V8 car would be less. I don't think you can do the 500" anything without going another couple grand at least. And keep in mind the roll bar you'll need. Better basic parts will perform excellently. So my build would go soemthing like this:
B based 451 using 440Source kit and the Indy SR EZ heads. The intake would be the M1 single plane with a 1" spacer if it fits under the hood. I'd run a solid flat tappet cam to keep things simple. The engine will run around $8K with the cooling system and carb/ignition. The trans, I would build a basic 727B, a Cheeta RPMVB, and the red clutches, and deep pan. $1500 w/PTC or TCC convertor. You sont need a Dana 60 for the 451 option. With moderate tires and leaf springs, it will live many seasons. So spool, gone thru, ring and pinion, etc $1000. I would leave the existing springs and stick some cal tracs on it. A set of /6 torsion bars is what you want.. free from most people...lol. So rear and suspension with good race shocks $2000. The rest of the cage, chassis connectors, belts, jacket, misc gage, fuel system, exh, wiring, etc will eat up the last $1500. You still have to put it all together, and the body needs to be done if it's rough now. The biggest cost difference is the dana and larger parts the 500"+ needs to be reliable in a bracket scenario.