[A-Snake]

"Thanks A-snake. Just what I was looking for. I notice by your profile your have a small block car: CSX2321. Were the measurements from that car and are they transferable to a 427 body style?"
The measurements are from CSX2321. Tonneaus interchange between original 427's and 289's.
Just for reference, your diagrams don't show the width between the soft top bow ferreules (50 1/2" ?), or how far back the soft top bow ferrules are from the back of the windsheild posts (32 1/2"?).
The distance from center to center of the ferrules for the top bow is approximately 48 3/4". I say approximately because the top of the seats interfere with the straight tape line.
I don't think a measurement from the windshield posts would help. That's why I used the snap at the center of the top of the dash. The windshield posts might be tapered differently than mine. Or located differently.
Look at all the drawings, remember there are 16 studs on the rear cowl.
"And what make of top were you using?"
It is the original soft top.