I have an 83 z-28 and I'm swapping a crate 350 that I picked up from a friend but I don't know weather to use the original intake from 305 originally on the car or a duel plane intake I found in the garagethrew the pictures which one would work best?

 

What are your end goals? The first manifold will allow use of different carbs while the second one looks to only accept a spreadbore type carb such as a Rochester. No sense in using the spreadbore manifold if you plan on a different carb later. jmtc

 

The 1st one (looks to be edelbrock performer), but man it looks to have seen much better days.

See if you can get the water neck bolts out with out them breaking 1st, then check all other holes, then try to clean it up .

 

I cleaned up the first one got the water neck bolts out and everything else on it. It actually looks pretty good do i need to put any of the sensors and the egr valve back on the intake because the "elderbrock performer" dosent have a spot for it?

 

Look in your 1st pic... Center, straight down at the bottom. See that plate with 2 Allen head bolts. That's an EGR block off plate.. Remove it and your EGR valve will bolt right up.