I have read where people trim the weights in the governor to change the shift point.
https://www.chevytalk.org/fusionbb/s...php?tid/283173
https://www.hotrodders.com/threads/c...ission.221004/
Here is a good thread on this forum -
http://67-72chevytrucks.com/vboard/s...4&postcount=19
Now to find out where to get those governors. Maybe Monster can help? -
https://www.monstertransmission.com/...or_c_5183.html
Do not attempt to adjust the shift timing with the throttle valve cable. The shift timing is controlled by the governor springs. For higher shift points at wide-open throttle, install lighter springs. For lower shift points at wide-open throttle, install stronger springs. -
https://transmissioncenter.net/shop/200-r4-tip-sheet/