Vortec 062 heads specs
Kendo grid event after read
Using Vortec heads is a great swap but you need to educate yourself before doing anything as they are just not a direct bolt-on. In 1996 Chevrolet engineers copied the port designs of the LT4 engines ( I think that's the one anyway) and put several versions on it's truck lines which included the 305 ci, 350 ci and 454 ci engines.