Moving onto the actual engine refurbishment:
With the engine holding compression I started working my way through replacing any and all gaskets and serviceable parts.
After removing the timing tensioner and pulleys I fitted a new water pump cover and gasket and cleaned up the water pump housing. Very straightforward (other than whoever installed the last one using a very difficult to remove gasket). I also had to helicoil the tensioner bolt holes and they had been cross threaded by whoever had installed them previously.
Next on the list was the oil pump gasket and it was there I hit my first issue. Initially I was not planning on removing the upper sump but you cannot remove the oil pump without removing both the lower and upper sumps. Not too big of an issue, it's bolted on fairly simply. Once I had removed it I was actually very glad my hand had been forced because it was in need of a deep clean.
With the upper sump off I was able to remove the oil pump. I gave it a deep clean and lighty lubricated the internal rotor before installing it with a new gasket as well as fitting new front and rear main seals.
Next, I moved onto the head with the goal of replacing both camshaft seals, resealing the cam cap cover and generally cleaning out some of the sludge in the head. Here I noticed more signs that the engine had been worked on previously to a poor standard. The exhaust camshaft seal was chipped and battered like it had been installed with a chisel. After cleaning up and reinstalling the camshafts. I cleaned up the cam cap cover, fitted a new vvti oil filter and prepared to reinstall the cam cap.
This is where I hit my first serious road block. The cam cap bolts would not torque down. Upon removing them they came out with the steel threads wrapped around them (either a failed helicoil or perhaps the factory steel threads.
I discovered the bolt holes were filled with gunk and oil which must have compressed and forced the threads out. I attempted to repair the damaged threads with a helicoil but there just was not enough clearance. The whole head was rendered useless by the damage.
It turned out my best option was to source another engine to swap the head from. I was able to track down a bare engine (sump, block, head) for a very fair price.