This is the cooling system I am going to try:
Similar to above, it consists of a pressurised header tank (psi of cap yet to be determined), just about the highest point of the system, though it's pretty tight, with top outlet connected to new rad (no cap), bottom outlet feeds into engine and outlet from cap when over-pressurised going to a non-pressurised expansion bottle, with the tube going down to the bottom so that when it cools, the coolant should get sucked back into the header tank.
Also a new E30 temp sender installed so hopefully that will fix the temp gauge issue.
Unfortunately I will have to wait until Monday to test whether it works.
Tim