should i just replace the rings an barings or should i just do it all crank an rods , an also i read that the oem parts can handle up to around 250 300 hp cauz thats all i really want so is that true or would that be pusshing alot on the oem parts
You should do a full rebuild. You'd better seriously consider modifying the motor so that it'll take the much higher combustion pressures. Things to consider in a rebuild of the motor are lower compression forged pistons, like 8.50:1 CR; magneflux crank/rod assembly; shoot-peen crank/rod assembly; ARP rod bolts; steel or copper alloy head gasket with O-ringing; studs for the head instead of bolts. These suggestions are just starters.
The OEM rods will take 300 HP as long as they are good shape.