WTF

Well, lets give it as shot to your shave head mod. DO about .010, not more than .025, be very careful with valve clearance. Not all is positive in thsi mod. By shaving the head, the timing is going to be affected because you are altering the height from the cam gears to the crankshaft. Usually a little shave wont be that bad. If you go crazy shaving to much, your car will suffer from heat, so be careful with modifying it too much.

Gains, Gains:::

Expect from 2 to 7 hp gains, all around the power band. One of the drawbacks of the DX block is it hass lower compression pistons than the LX. The pistons can be swapped, but that is another 20 bucks you are getting into. I have done it many times, from LX to DX, and DX to LX for tubo applications. THose DX pistons worth gold in a 1.8 turbo.

Hey, anyway good luck, try to have a spare head before doing that or know where to get them cheap, sometimes the machine shops are not that precise and can mess them up. Besides that, it is a #2 difficulty in a scale of 5.