Worth it to build my 273?

Like Perfacar mentions, et is in the chassis, MPH is the HP.

It takes about 275 rear wheel HP to go 12.80/104 at 3300#. That's going to take around 325-350hp at the crank depending on drivertrain efficiency. It's a bunch easier to get that from a 340 or 360 than a 273 and it's a SIMPLE build with nothing special. 360, kb 107's, Comp XE268H, stamped rockers, stock 1.88 or 2.02's, LD340/Air Gap, 750DP, headers and decent ignition... DONE, 350ish HP.