hit the water jackets on the inlets no worries just fill with devcon
http://www.pitroad-ts.com/tuning-page/Ts-cup-2/ts310-engine.htm







the reverse D port could increase the tumble as there is already enough swirl in the
A series chamber design but manifold would be a killer to do.
The original poor short turn radius on A series heads could be there to keep the charge
on the important part of the valve not right across it which could create undesired eddys.

keeping the charge together as tight as possible, as deep into the downward piston
swirling tightly away from the cylinder walls is crucial and short turn radius opened up
sometimes disturbs this desired flow characteristic matched to the chosen stock chamber.

A small cc due to shaving the head for comp can also be upset with increased short turn radius
as it could prefer deeper set valves. Its all very tricky to balance a real art.
As a natter of fact this mod showed no improvement in some race applications so Nissan
engineers know alot more than us tinkerers