Alright....if I'm not on the right path please set me straight because I'm learning as I go and I havn't gone very far yet!  428 with a c6 transmission and a knock has been noticeable after warmed up.  A friend with a good ear and loads of experience under the hood figures the knock is possibly coming from the torque converter. He said the late 60's Ford converters had issues.   I've researched most of tonight and began to wonder if the flexplate could be the source or linked somehow.   I've had consistent issues with the starter not engaging, with an audible spin/whirling noise finalizing the attempt to start. Not a grinding. The whizzing almost always happens from cold starts.  A few tries and she fires up.  After the motor's been running I think I have heat soak issues so that's a whole other problem a hi-torque starter may solve.  Could the flexplate be out of balance which results in the knocking and also potentially a reason why the starter will not engage all the time?  The knocking is when its warm, where I've also noticed my oil pressure is running quite low at idle, 5lbs or below.  Up to 40lbs when driving.  Blow-by / blow-back.... I have an issue there so I'm due to do a rebuild I'm betting.  So what should I do/check first?  I was told to disconnect the converter and start the engine up and see if she still knocks.  If so then I focus on the engine but if the knock is gone then we know its plate/converter related.