You are correct Wiggy it is oval port as per your description. As I said learning as I go. Think I'll retake the inlet manifold off, house out ports and see what happens. cheers all. PSR

I doubt any restriction caused by D port vs Oval gasket shape would make it overheat so fast.  You should do a compression test.  If it fails you probably have a head gasket problem or cracked head and it will tell you which side is the problem.  If it passes then its probably the inlet manifold side of things. A compression test will take a lot of the guess work out.

I have a new problem now and require suggestions please. Thanks for the advice so far. The car is running kind of lumpy at idle and have timed it and it overheats at 20mins not 5mins. Temp gauge still no go.
The oil pressure gauge line has been blocked off at side of engine with a screw and at last couple of runnings the screw has shot out of end of line and spewed oil every where under excessive pressure I assume. Is this all related to the head and manifold problems.  Any suggestions? Cheers Paul
 

P S Robbo
I just used standard composite type gasket with sealant

??
I wouldn't have thought you would use sealant on a head gasket, but I've only built Pinto engines.
What sealant did you use?
 

Hi , I used Copper Gasket Spray Cement on the head gasket and Permatex Anaerobic red gasket maker on the Inlet Manifold.  Is that OK?

Head gasket should go on dry and block and heads checked for warping first. Otherwise it’ll leak or worse crack the heads.

Inlet manifold gaskets have a copper heat shield around a water jacket, these can come loose and move blocking the jacket restricting flow.  Easy job to  remove and check the inlet gasket

Thats a question I was going to ask. With the inlet manifold gasket--  Does the copper heat shield side face down against the heads or face up against the inlet manifold??   Maybe I put it on upside down.