More importantly, if your mechanic has done this head machining he has no clue of what he is doing. I shudder to think what he is going to do with the rest of the engine. If he is so bad then he cannot be trusted with any other mechanical jobs - gearbox, suspension etc. You need to quickly tell him to stop all mechanical work and find another guy through the help of Pakwheel guys. You are in Karachi where there are hundreds of good mechanics.
To add more to what Zulfiqar and Arslan Sb. have already said, normally the compression ratio of your engine would be around 9:1 of even 10:1. That compression ratio is suitable for 86 - 93 octane petrol. By machining the head as much as your mechanic has done the compression ratio may have gone as high as 11:1 of even 12:1. That kind of compression ratio is found on formula 1 race cars running on racing fuels based on alcohol. When you try to run you Mazda with this head on regular petrol, you will have all kinds of issues like overheating, knocking, irregular idle etc. I think even the pick-up will be effected. As Arsalan Sb. said your only option is to find another (un-machined) head.
For future referrence, a cheap and fairly accurate way to find if the head requires machining is to take a thick (8-12mm) glass a few inches larger than the size of the head, apply a very thin layer of engineer's blue (Prussian blue artist's oil paint) on the glass. Turn the head over so that the face of the head is upwards. Place the glass on the head with the blue facing down on top the head. Move the glass in a figure 8 over the head allowing the blue to rub off on the face of the head. Lift of the glass and look at the head. If the head is good you will get and even blue all over the face and if the head is bad, only the raised parts of the head will get marked with blue. Once that is done then one can decide if a head skim is required or not. I personally prefer lapping the head rather than machining.