well the vortec heads flow pretty well for factory heads and that cam is ok. idk about a 100hp though. i think making 1hp per cube with the 305 is kind of tough. id be surprised if it didnt pick up around 70 80hp though. like i said in my earlier post if you intend on running that motor, if it has alot of mileage on it your going to want to do bearings. i wonder what kind of compression that motor will make with the vortecs on it. if theyre 350 heads id be surprised if the combustion chambers arent bigger than your current heads causing you to lose compression. if thats the case you might want to check out paw for a cheap rebuild kit with flat top pistons and search for a set of vortecs with combustion chambers that are similar in cc to your current ones. your going to want more compression not less if your going to try and hit the 300hp mark.