I'll give you my thoughts on your broadcast sheet question;
SEQ#: refers to the sequential number of your G-Body car on the date shown at Fisher Body BOC Flint (includes Monte Carlo, Cutlass and Regal)
DATE: production of body only at Fisher Body. This date is one working day before the final assembly date at CPC Pontiac. Your original coil pack should have a date decal to verify this difference.
BODY NUMBER: this sequential number refers to all g-bodies produced at Fisher Body and would include Monte Carlo, Cutlass and Regal. This number should match the body number plate located under the driver's side windshield on the cowl.
LINE NUMBER: very close in number to the body # but not the same. I think it refers to the sequential number for CPC Pontiac final assembly. In other words, includes all the above mentioned g-bodies to roll off the line in Pontiac. This number should appear on your Service Parts Identification trunk sticker, just to the right of the VIN. I believe this number also appears at the bottom of the window sticker, to the right of the VIN.
*NOTE* Keep in mind that both the body and line number got set back to 000001 around Monday, August 3rd, 1987 when Pontiac started production for the extended-build 1987 Grand Nationals, 1988 Monte Carlos and 1988 Cutlass Supreme Classics.
Tom
P.S. Just my thoughts, others jump in and comment!