Good news! I contacted Bildon, and they said that they have, or can get, 11 mm Raceware or ARP head studs (I'm not sure which). I think I'm going to go ahead on this project. The worst that can happen is I'll blow the little motor. Since they're basically being given away for free, I'll just get another one, or I'll take all the mods and put them on a 1.6.
I want to track the evolution of this thing. First I want to get a couple of bone stock quarter-mile runs. Then I'll put on the GTD nozzles, air dam, lightweight flywheel, synthetic oil, and adjust the fueling. I'll do a few more runs to check the improvement. Then I'll install the turbo, exhaust, and windage tray and run again. One of the last things I'll do is add an intercooler or water injection, install high strength head stus, and increase the boost.
Depending on how this projects goes, and if I think there's still room to grow, I'll add an oil cooler, larger radiator, Ti valve components, lower compression ratio, thermal coatings, forged crank, etc. I hope she holds together...
hehehehehe, turbo on a 1.5.......better figure out how to cool the pistons. I think you can use the 1.9 metal head gasket if you block the extra oil hole somehow, might try that. I am very interested to see how long a 1.5 will last with all these performance mods. They used to crack their engine blocks and mix their coolant and oil together after about 100K in a rabbit in normal 48hp stock configuration.
I think a definite must, would be coating the tops of the pistons with at least ceramic. That would definitely help keep the pistons from melting. As for the head... coat that too if you want to turbo it. Your motor will be happy, and you will be happy for not blowing it. Also, open up the exhaust, and get yourself an EGT gauge at the very least.
As Chrissev said, you should be more worried about cooking the motor than blowing the head gasket.
Alternatively, I would suggest supercharging it. Check this out:
http://vwdiesel.net/phpBB/viewtopic.php?t=3643&highlight=supercharge
Before I do anything too exotic, I just want to get the thing put together and running. I'm hoping the engine will prove durable enough to justify spending more money on it later. If and when I do pull the head, I'll probably do just like you said and have it thermal coated. I'll also put in sodium filled exhaust valves if they're available. I'd also consider titanium if somebody makes them.
Obviously, cost is a concern, and I think it would be cool to pull the stock pistons, have them thermal coated, and put them right back in. I would LOVE not to have to pull the motor and tear it apart to do this.
I have considered supercharging it, but I'm concerned about parasitic power loss from the S/C. This small amount of power this little motor can make needs to go to the flywheel instead of turning a S/C. I also don't think the S/C is capable of making the kind of boost I hope to eventually have.
An EGT gauge will be among my first purchases. I won't run it any harder than the EGTs will allow without the thermal coatings.
The principle idea is to use the high-RPM characteristics of this motor to make HP. 100 ft./lb. at 6000 RPM is still 115 HP. Hopefully this isn't too much to ask of it.