This is my first complete 350 build, so please understand that it has become more of a hobby than a profession for me. I have installed the 083 heads on my roller block thinking these would be the best choice, but the TPI lower manifold (Part #14081005) that I currently have will not line up on the center holes. Manifold was test fit without gaskets. It appears that I would have to modify these bolt holes, but they would be very close to the outer edge of the manifold and would loose the integrity of holding the manifold in place (Please correct me if I'm wrong here). I'm wondering about using the newer manifold (1088015) that will fit the heads. Is this a speed density only type of setup or can I modify what I already have. I have all MAF parts including the MAF sensor, runners, upper plenum and most of the sensors. I would appreciate any advise or opinions and thank you to all of the experts of this site who choose to reply.

By the way, this is going into an 86 IROC, but most of the parts that I've bolted on (including the serpentine belt setup) looks to be for the later 89 models. There is currently no ECM for the car and I have all the wire harness out while I work on restoring the body.
Thanks.

 

I know this may seem simple to alot of people out there. I was hoping on getting some opinions though. Thanks....

 

elongate the 4 center holes.