you can put the ball too out in front, basically theres no magical spots, just keep the pam off. your fingers can touch the ball like they want, they are what are giving you those extra mphs.just get something comfortable and throw it hard showing the inside part of the ball to the catcher. dont change anything in your mechanics, just play with how you release the ball and what type of spin you put on it.
since you are a big guy, you might throw hard? if thats the case, you could try and do the exact same thing but with a 4-seam grip. you will get tailling action on your 4-seam fastball, maybe a little less sink but since more seams are rotating throught the air you will get more tail. pedro martinez, in his prime pitched primarly 4seamers but placed it well and had good tailling action because of the spin he would put on it.