Matt Im sure you have thought of alot of things on this journey
but I have to pip in just in case of my conscience....


I have a cooper mini on the side and have to say the heads are
very nicely designed in terms of the water thermostat at the front
much like some older Nissan H20 and R16 fairlady OHV engines.

Would think this design feature is better as it would allow use
of common thermostats or mini parts rather than NLA nissan bits?

Mini billet head seems to stick with non angled ports to clear
the original Austin or Rover mini bonnets where a datsun would
have no issues with raised and angled inlets, just something
you might consider.

Lastly the exhaust manifold stud patterns could be
designed to suit a modern engine like the Honda D16 as the
aftermarket parts for these are dirt cheap and plentyful.
Inlet manifold Im sure you got that worked out.
Which ever way you go for exhaust ports, just allow 1 to 2mm
smaller size than header to reduce reversion rather than
match ported to suit headers.