Sorry for so many questions however we need more info to help.
Can you tell us more about the oil pressure you have?
Once the oil is fully warmed up what is your idle pressure and also what is your pressure at 4000 rpms?
What cam did you have installed and was the base circle the same as the stock cam?
Did you degree the cam?
What is your total timing with vacuum advance plugged and engine revved up? Shoot for 32-34 degrees total timing
Have you adjusted the idle mixture screws on the carb to get a nice smooth idle in gear?
Watch the video of my stock 73, your engine should peal the tires no problem.
70 Skylark-Twin turbo 350 powered
and 18 spare Buick 350s in the barn.