240 B23E with oily intake

I'm doing a head gasket on a B23E.

There is a significant amount of carbon build up inside the intake manifold, but I don't think this engine has been neglected (underneath the cam cover looks spotless) and there are no oil leaks so the oil trap is most likely not blocked (I am changing it anyway).

Is it a good idea to not allow the engine to recycle what's in the crankcase and run the oil trap breather hose to somewhere down by the frame rail like the good old days? I will replace the entire flame trap and oil trap system and all the hoses, but I don't like the amount of oil that was in the inlet and throttle body. Is it normal to have some black inside the inlet ports?

I'm getting the injectors serviced too

Yes, technically you could vent the crankcase to the atmosphere. But you would need to close of the port on the intake manifold.
I assume you know it is not environmentally acceptable. You might want to check the law in Aus.
I think the blackness in the intake ports are the crank vapor deposites Normally those ports should look like clean aluminium. Specially the part where the injector spray cone sprays fuel onto the valve and port area.

The engine is internally sealed better when the crankcase is under the vacuum of the pcv system. I'd double check the drain hose and also check the mixture. That's a kjet engine isn't it? Someone may have richened it up too much. In a kjet engine you get a lot of fuel varnish in the intake with the cold start valve spraying right at the throttle body. In the kjet manifolds I have. There is a large buildup of carbon inside the manifold from the years of use.