oil pressure fluctuating.

2 items come to mind.
- You switched from 20W50 to 10W40.
- You switched to roller lifters from solid lifters.

Each of these may have a small impact on the pressure. The roller lifters may bleed off a little more pressure due to clearances. The oil is a little thinner.

You put on the EFI. Did the hot idle speed drop? If yes then this may be contributing a little to lower pressure. Nothing to worry about.

The numbers you are posting are decent pressures. Have fun driving the car.