building 273..or not

Really depends on what you want to do with the car, as has already been mentioned. If you want a strip car the 273 is not your best option, you can make a lot more horsepower for a lot less money with a 318 or 360.

But, if you want a driver you can get plenty of power out of the 273, and it will get better gas mileage to boot. Most moderate modern rebuilds can get a horse per cube, there's no reason why you couldn't get close to 300 hp out of that 273 and still have a very streetable engine. Up the compression (although I wouldn't go over 10:1 in CA with our fuel), get a more modern cam grind, keep a small port intake like the Street Dominator and a 600 cfm carb, go electronic ignition and get a set of headers. 300 hp in an A body will get you in the low 13's on the 1/4, maybe even the high 12's depending on your set up, traction and driving ability. Plenty of fun for a street car.

I see you're in Berkeley- if you do decide to build something else, I have a complete, running '74 318 I don't need. Should probably be rebuilt, it smokes a bit on start up because of the valve guides but it was running when it was pulled. I also have a '74 360, complete, partially torn down but all there. Its high mileage with a couple low compression cylinders (rings), but its std and would be a great core. You can PM me if you're interested.