Thanks, I wonder how a person might come across some euro manifolds? Do the 560 manifolds fit the 420, since the engine is similar?

Does the 4.2L and 5.6L share the same block and heads and it is just the bore and stroke that are increased to make the 5.6L?

I wonder if there are any European members on this, the tech side of the forum? I am normally on the diesel side and there are members from Europe over there I could perhaps ask, but this side would be more familiar.

My brother and I are fixing this for Dad since his Chevy is falling apart and we got it for cheap since the chain tensioner failed and the timing skipped. I think that if we can find some euro manifolds we will just run dual exhaust straight through some glass packs and out, if back pressure is not an issue. I have the flanges off the single exit manifolds from two engines so we could just use those and have new pipes bent from the manifolds back to the glass packs and out some nice cheap tips.