To me, a "1hp/inch" build does not apply to a never-factory-offered build. I.E. 500" mopar. Once you go outside factory parts the pricing I think is more accurate would be for a 440 that has to make that 550hp. Because you're buying parts you might otherwise refurbish, your modifying parts to move the air you need and buying larger components, your spending time engineering parts to fit into the block, you're doing more just to get it together. A 1hp/inch 440 can be built very solidly, for about $5000. A 1.25hp/inch 440 (550hp) will cost another $4K plus for more cylinder head, better pistons, better rings, more block reinforcement, better pushrods, better rockers...
