Member @Treblig was making magnum manifolds for a-bodies... Not sure if he's still doing it, but he may be able to let you know if the magnum exhaust manifolds may work with an early A body...
I have talked to him and he does not make or pair these together anymore, trying to remember where my notes are, (in the shop I bet) but here is some info I got from another members post @Slantsix64
You can use a 1973 340 manifold on the driver side, 2.25 exit size and a 96/97/98 Jeep Grand Cherokee passenger 2 1/8 exit on the passenger in an Early A Body withoutpower steering.. I am still looking at using my new Hookers (Fender well) headers , just pilling up some info, and I will be moving this thread one day
Thank you again @krazykuda