This will kill you

[JB400]

How'd this turn out?

[Cooter]

Judge Judy's Court I suppose.

[ACUDANUT]

Gonna leave us "hangin"

[1974dodgecharger]

dont they all leave us hanging....

[lexxman]

 Did you find the problem?

[vegasmike]

same noise happened to me,I had four bent pushrods

[hatersaurusrex]

Sounds like he was trying to impress you by showing that he knew how to rev the engine from from outside the car.   OMG WHAT AN EXPERT

[StockMan]

A quick update on this (sorry for leaving everyone hanging).  
Well last winter I pulled the 383 and freshed up a low mile 440 that I installed this spring (2012).  The noise was still there!  After driving it for a while, I began to develop a trans fluid lead, and I noticed that the torque converter was draining back at a much higher rate than it was previously.  The tranny did have a new seal when installed.  Later in the summer, maybe 400 miles later or so, the 'Chirp' was gone.  I am in the process of pulling this trans in place of another that I have here that is completely rebuilt by a reputable place.  Its a later model 727, 1975 vintage.

So, it ended up being the trans after all that.  I still have the 383 intact and will probably freshen it up later on and re-install it.  My goal was to try and stay as close to the stock condition as possible.
It was odd to say the least, I had many people listen to the sound, and nobody could figure it out, and nobody even came close to suggesting that it could have been the trans.

I'm not sure what the rev could have done to the trans, I don't know to much about the internal workings of the 727.  It did have 96,000 miles on it.

[FLG]

Could be the flexplate bolts backing out...common thing if there not loc tighted in.

[StockMan]

The flex plate bolts were all tight when removed.  I am going to have the trans looked at, and probably rebuilt so hopefully at that time I can see what the real issue was.
I wish I could have figured it out before swapping motors though.  That being said, I installed a crane 'Fireball' cam in the 383 which probably took away from the power. 
The stock 440 pulls quite a bit harder.  The 440 is a bit sensitive to fuel though, likes premium, and even them I get the odd ping.