Mohican Polled Herefords, Glenmont, Ohio bred Broker. Although he was huge, he did transmit some milk into his daughters. Not like many other's in the 80's. My first purebred cow was a Broker grandaughter.
Lots of bulls to pick from the 80's to increase size. If I was to do it, hunt down semen on either:
JR LB 621 CHIVAS Y168
JR LB 621 STEALTH A99
JR LB 621 COSSACK Y166
They were all full brothers (scurred) and their mother 'Crystal' and sister 'Cassandra' were just gorgeous cows for the time - best to ever come out of the John E Rice Herd. Based on where the breed went in the 80's, they were far ahead of their time in terms of function and udder quality. I was the last person to register offspring in this country off Chivas. AHA records say that SK Herefords
http://www.skherefords.com/bulls.htm has US rights to him. I would buy a good son off one of those bulls in a heartbeat. They were mama makers.
If your not worried about udder quality and just want nice big deep barrel mama cows, many of the Butler bulls did just that. Nick the Butler P183, Domino 15G, BT Butler 452M.
If you want frame size and nothing else, Glenkirk bulls are your poison. GK Turning Point X53 was huge, 8-9 frame. I used his son, GK Tradewind Z8 and cows were just monsters that didn't milk. Turning Point's brother, GK Rushmore Y8 was used a lot to add frame. He was one of the biggest I remember, I think a frame 9.2 or 9.5.
But those big frame bulls also can have cow killer birthweights - 130-150 lbs. And the calves will starve because the daughters had no milk.