pushing out the coolant

i have a 96 with a lt-4 engine. in my driveway, i noticed steam. the water pump was leakign out the weep hole so i replaced my water pump knowign that if ther bearing goes bad it will leak there. luckily the optispark was ok. now putting antifreeze in has become a major issue. i filled the radiator and surge resivior ( i think thats whut its called) and the over flow. as the car gets hot it is pushing the antifreeze into the overflow. when i shut it off it all boils out of the over flow. im almost positive that the coolant i put in istn enough. when the engien rev higher itll pull antifreeze down btu when it jumps to idle it pushes it all back otu again. both hoses get preasure and hot. a gm tech i knwo told me that a blown head gasket leaking compression into the coolant system would cause this. also the car has higher miles. i tried all thew tricks ppl told me about that and that it is a task to fill coolant. i was wonderign if anyone knows a trick or if sumone has had a similar problem.

thanks,

Did you bleed the system?. With the bleeder screws. Its normal for the over flow to overfill though if you overfill the system when its cool.

yeah i tried that i got more in my jackin up the front of the car but now its running at about 204 degrees