i dont know where you hered that porting your heads will ruin them. but you cant go wild with the ports they are thin. but you can smooth out the castings and the intake ports. you do not want to change the shape of the ports this will have a neg. effect on the flow efficiency. bacicly all you will be doing is what is reffered to as a pocket port. some power is also found when you port under the valves. some heads are real restrictive there. as far as the t/b goes do a search on z-24 cavilers, i seen a ready to install bored t/b on one of those sites. GM sells a real nice cam for those motors also. think turbo for some nice power. buckeye has a perfect one for that swap