I ASSUME THAT YOUR 454 IS IN YOUR '69. I HAVE A 68 454 WITH HOOKER SIDEPIPES AND THEY FIT PERFECT. I DO BELIEVE THE ANGLE PLUG IS REFFERING TO A SMALL BLOCK. I HAVE NEVER HEARD OF A BIG BLOCK WITH ANGLED PLUGS. THERE ARE TWO DIFFERENT MUFFLERS AVAILABLE FOR THESE SIDE PIPES THAT YOU NEED TO BE AWARE OF, ONE IS VERY RESTRICTIVE AND THE OTHER IS MORE LIKE A GLASS PACK. THE GLASS PACK IS QUITE ABIT LOUDER, BUT DEFINITELY INCREASES THE HORSEPOWER. THERE ARE ALSO BAFFLES THAT YOU CAN GET FROM ANOTHER COMPANY THAT REPLACE THE MUFFLERS. EVEN LOUDER, BUT EVEN MORE HORSEPOWER. IF YOUR INTERESTED IN THE BAFFLES I WILL HAVE TO FIND OUT THE NAME OF THE SUPPLIER, I JUST CAN'T REMEMBER IT AT THIS TIME, BUT THEY DEFINITLY DO THE JOB. THE COPS HATE THEM.