I think the Howell unit is a 4 barrel one or a bored out 454 throttle body. Either way it won't work on your setup. Stock manifold has the same size bore holes as the stock throttle body, this means you can't put a larger throttle body on and get any real benefits. Its like breathing through a straw, cut a little off the straw, you are still breathing through a damn straw! Need either to upgrade to a carburated manifold with an adaptor with holes to match or Holley makes a TBI intake with 2" bore holes. On my 89 I will install a 454 TB(stock 2" bore) and Holley intake.