273 vs 318

No secret here..... If you bored a 273 .060 over (but kept the compression the same), would it be capable of more power?? Of course, the answer is yes. You just added about 10 cubic inches.
A 318 is a bored out 273 by the tune of 45 cubic inches. If both have the same cams, intakes, carbs, heads, exhaust, and compression, the 318 is going to out perform it every time.