You need to treat the 273 like a 283. If you know the original history of the 273/4, it bested all the sb until the 283/4 showed up. There is a reason that TRW made a .070 high top piston or the 273. It will take a .060 without any problems provided the core checks out. Then its the heads and very good machine work. There's plenty of power to be made. Its just not going to last as a daily driver.
