FP for sure - regardless of your fuel system upgrades/age. i second the trans temp gauge . . .
i would go with mechanical FP - super easy hook-up and more reliable IMO. no need for an isolator - just make sure your connections are good and run a needle valve to dampen the pulsations from the IP. the pulsations can be hard on the gauge if not dampened.
i would go with mechanical FP - super easy hook-up and more reliable IMO. no need for an isolator - just make sure your connections are good and run a needle valve to dampen the pulsations from the IP. the pulsations can be hard on the gauge if not dampened.