Hi Aidannn
The L28ET's in the US use used a head called a P90. It has larger combustion chambers to lower the compression ratio to around 7.4:1 from memory. In my opinion this is too low and will result in a lack of response.
For a budget L28ET setup I would simply use a standard n/a 280ZX engine with the compression ratio of 8.3:1. You could go a thick head gasket to get it a little lower as herrods suggested. If you get a decent intercooler, good engine management, run it on 98 fuel and run around 10-12psi you should be able to get 150-200rwkw depending on what other bits and peices you use. This is the basics of the initial setup when I bought my car and it was good for 174rwkw with excellent response and torque. Make sure you buy a computer that controls fuel and ignition so you can pull back the ignition timing when it comes onto boost to stop detonation without loosing response.
Don't worry about the lower power figure, it will have a truckload more torque than your mates Honda.
I'm now running a modified P90 head and flat top pistons to get around 8.0:1 compression but this is not worth the trouble really. I now have 265rwkw but the biggest gains have been from the turbo (switched from a t03/04 hybrid to a GT3540R), and fuel (I'm now running Sunoco 260GT0. This allows me to run 21psi boost.
My build thread can be found here.
http://www.viczcar.com/forum/index.php/topic,2662.0.html