I'm currently replacing the cyl head of my 1.8 Turbo '84 Sunbird and wish to improve power and reliability in the process. I already have a rebuilt 1.8 head. The bottom end has about 8k miles since rebuild. Swapping the engine for a 3.1/3.4/3x00 is not an option right now, since I am also buying a beautiful survivor Fiero this week. The stock rating is 150HP (less @ RW, I'm sure) but I'd like to get an honest 160+ RWHP. So, here's what I'd like to know:

1. What was the name of and where can I buy this better head gasket that I have previously seen mentioned here (some kind of multi-layered steel head gasket)?
2. Is there an upgrade camshaft available for the 1.8 OHC that works with the turbo? Is the lift different from the 2.0 turbo cam and are they interchangeable? If the 2.0 cam has the same basic dimensions but more lift, could it be swapped in to the 1.8?
3. Is there an adjustable cam sprocket? Maybe a multi-keyed sprocket from another application which would fit this engine? Haynes says my cam is supposed to read 10 deg BTDC at the crank pully with a new timing belt, but mine reads more like 6 deg BTDC with a new timing belt. When I tried one extra tooth difference, it makes the crank reading about 15 deg BTDC which doesn't run good at all. My checking is according to the fixed crank timing indicator which doesn't show any evidence of being moved or damaged.
4. I have briefly read around here that there are other iterations of this Brazilian-built engine (1.6L and others?) that have been used world-wide. What parts are interchangeable with other world-wide engines and where do people buy parts for them?
5. Any other performance improvements that would really be worth the cost (not looking for $350 fuel injectors that add 3 HP, or reduction pulleys that add 5 HP). Example: I am able to do some port matching at intake or exhaust if that would help, and I can change out the wastegate or add electronics to control/increase boost, if the price is right (not seeking engine management for $750+). I'm looking for what makes sense before I put the replacement head & cam carrier back on. Rather than imagining playing dyno doc for me, please offer advice that has shown proven increases for you or others. I am trying to make reliable power improvements as this is a family driver used by my wife and son. Thanks for any help.