overheating and need some horses before swap

[v-slo1.6]

so ive got a 95 sol ive owned for over a year(first import to own so new to the game), done some mods, both visual and performance, and just as i am getting all together for consistency i am overheating as soon as i hit the highway for more than bout 30 min, at a constant speed?? i can cruise town all day, maybe run warm , but i hit the highway and the gauge pegs, overflow boils and radiator mysteriously is near empty, i replaced cap,thermostat and fluids onlya few months back..and doesnt apear to be leaking i am hoping its not a head gasket anyone with any ideas.. i am gonna try taking out my thermostat for a bit.? i am also interested in sqeezing out some more power out of the little beast,, yanking ac and maybe power steering.. how much power will i get, or should i say is it worth it , ac dont work anyway.. and finally how pricy would a turbo kit be for my sohc 1.6 and would it sprool to fast with vtech? or a good combo.