I don't know why anyone would go through all the trouble to try to shoehorn an RB motor into an early A body, unless it was strictly a drag car! It is a very labor and fabrication intensive operation, and costs waaay more than it's worth! Forget about just the headers, you would need a motor plate or torques straps just to keep the engine from hitting the hood, which has very minimal clearance when it's not running! Add the weight of that motor to the front of an early a body and its nod surprise that they handle like crap! With all of the power available in stroked small blocks, a big block has too many drawbacks to make it a viable option! There is not much info out there because it simply isn't done much, for the above reasons!!