Considering the 1.98's can give power gains of around 20rwkw, at $650 it works out to be around $33 a kw gain, which is very good value for money in anyone's language
if he is that tight to buy anything from the cheapest performance parts for commodores i think he should either scunge up money to buy a V8 or just not get anything done, by the sounds of it he is looking to have a fast car for only 200 dollars and everyone knows thats not going to happen.