["Hope everyone confuses it with BRE"]. Haha! We'll try.Three words about your complaints:
(1) Fuel pressure should be measured as close to the carbs as possible, since that's really the only place it matters. Some fluctuation is normal, but that close to the pump you would get wild readings because you're measuring pressure so close to the hi/lo source and it hasn't had time to build up in the fuel line yet, so you're actually measuring spurts of pressure, instead of constant pressure right outside the carbs. Try moving it downstream to the fuel rail area.
(2) I had Tach problems for years after swapping from the stock breaker-points ignition to electronic ignition (which no longer required an external ignition resistor). My Tach would lay at "0" for hours. On long drives the Tach needle rose slowly but steadily until it was pegged at 8,000 rpm, so it was getting a signal from somewhere, but it was unusable. When I cut the ignition the needle would fall back to "0" and start over again. Very weird.
When the stock resistor (which was no longer needed for the distributor) was re-installed, the Tach worked again. So the resistor isn't needed for the electronic ignition, but it doesn't hurt it, either. It is, however, needed to keep the Tach happy. Or, you might just have a dead Tach or an open circuit somewhere.
(3) Using the terms "full throttle" and "cold" in reference to a Z engine makes me grind my teeth. Please let it warm up first?