[EJ251 - Honest opinion, should I even bother with this block?]

I have been running the 96 to 99 2.5 naturally aspirated engines for years and many long commuter miles. I have only had trouble with the 05 turbo version. I have learned to do the maintenance regularly and never ever overheat them. Because of my experience I would still use them. Just expect every hundred thousand mile to do head gaskets. At two hundred thousand be looking for a new block. My favorite mechanic Allan @ double j said never build a block with over two hundred thousand miles on it. He said it just would not be a reliable rebuild.

[04 baja turbo oil leak ?]

Have you checked the oil cooler right above the oil filter? it may need new gasket...