could i replace the headers and intake with 86 and older heads and intake? these would be at the same time....i know the intake pattern is different but is that it? is there any performance difference? this is on a lo3 305 because seems like 86 and older stuff is much cheaper

 

Yes, you can. Other difference is the crank, you'll need a different flywheel/flexplate...but since (from other post) you have the whole sha-bang, you should be good to go.

 

TBI,

The rest of the head-to-case bolts will align the same on either head. The cooling passages are in the same positions. The only other differences are that the '87 will use shorter push rods, but that is due to the roller lifters, not any head dimensional differences.