Early A Big Block And Motor Plate

That would be a huge help! On the exhaust, I'm not sure yet. I am either going to make some factory C body manifolds work, or my friend Matt says he can make headers for anything. I've already seen his work and it's very good. He's a Chevy guy though, which has no bearing on his talent, I just don't think he knows "how little" room he has to work with. He assures me though he can do it. We'll see. It's a long ways off yet, but I am trying to get all the hard parts done NOW, because the cost is just going to keep getting worse over time.

Sure - I'll take some measurements tomorrow. If I recall coorectly, I think I followed the TTI measurements for the later A-body big block cars (http://www.ttiexhaust.com/MoparClassics-Headers/400IB-218/TTi400IB_Install.pdf). I'll double check tomorrow. I do know I mocked everything up and aligned the crank centerline/trans output shaft with the pinion yoke on the rearend before I locked everything down.

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This may help too: early a body big block engine mounts

I've heard angle milling some manifolds may work. I've also seen a couple guys swap sides and run manifolds out the front and under the k-member on the way back. A guy - Ron Thomas "Chassisman" over on Moparts has an early valiant with that configuration - https://board.moparts.org/ubbthreads/ubbthreads.php/topics/1990015/1.html. I'll see if I can find photos.

Either way, it sounds like you're well on your way to the BB early A club. Can't wait to see the progress.