Loud in neutral could indicate a siezed pilot bearing. It will beat up the end of the transmission shaft so replacement should be sooner rather than later. Any vehicle that sits that long can have problems from gummed up fluids; especially brake fluid which has an affinity for accumulating moisture. You might want to pop off the clutch slave cylinder and check the the o-ring seals and cylinder walls for corrosion/wear. Fresh Lucas? In what? Transmissions are pretty picky about lubricants. My 2x4 takes plain 30w non-detergent motor oil. Did you put the right stuff in?