273 Performance build possibilities.

you have a 318, why not just build that and dress it up like a 273?

400hp is somewhat easily attainable from a 318. or you could even stroke one out to 390 and get there even easier.

a 360 makes that same 400 with a boat load torque to back it up for less dosh eight ways from sunday and twice on monday with no high rpm drama.

but to answer the initial question: yeah, sure you can build a high hp mega rpm monster 273 and spend a TON of cash doing it. the usable power band is going to be narrow and peaky and it'll have terrible street manners, but it'll be fun before it eats itself.