70 Dart S6 to 383BB conversion - Cast Iron Manifolds

Guys,

My motor build will be mild. Purple cam, mild compression, roller rockers, tunnel ram with holley 400's. Headers that will fit are well over $1000+ additional parts. My engine builder says I can just use stock manifolds with no performance sacrifice. My issue is the manifold set I have I don't know what model car they came out of. My 383 is a date coded May 1970 but I think it may have come from a monoco or something larger than an a body. I'll post pics. The pass side turns straight down to the ground and I think that will work fine on that side. The driver side flares out 30 to 40 degrees maybe? Towards the drivers side frame. We all know with the z-bar linkage and the torsion bar the drivers side is challenging.

Can anyone tell from the picks if these might work for me. I don't have the engine right now. It's with the builder. I'll have it back in the spring and I'm trying to stay ahead of slow downs/challenges. Appreciate anything you can offer other than $1000 to $1500 in headers. My budget is very low. Thanks, again!

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