WT
there's no reason to have it much higher or lower than the hose nipple on the filler neck. For reasons that don't pertain to the C34, on my 30 the reservoir is much higher, and yes, coolant does spill out the manifold unless I pinch off the hose. I need to put a small ball valve on it. I'm probably telling you what you already know, but the reservoir simply fills by coolant expansion and the pressure > 13-16 psi bypassing the cap, and it replenishes the engine by the vacuum created when the coolant contracts, so it can be higher or lower, but..... why? The spot you note is fine.
If you are leaking when you fill the reservoir, it's either the cap or the filler neck that is bad. Someone recently had a cracked filler neck. I ass/u/me that the hose fits tightly on the filler neck and you tiny-hose-clamped it? Note that there is a slight benefit to using clear tubing (can see air bubbles exiting to the coolant reservoir.)
Let me know if you have questions on the other when the time comes.
Are you in salt? Keep that Sherwood pump in good shape (it's an iron body pump and corrodes and if neglected the shaft can seize.) That will ruin your day as it can snap off the fork on the camshaft that drives the pump. When it starts leaking, consider an Oberdorfer (bronze) pump.
good luck!
ken