5.3 vs 6.0 manifolds

[SRT10KLLR]

Are the stock 5.3 truck manifolds the same as the 6.0 manifolds?

I ask because I am installing a 408 and I noticed that the 5.3 heads have "O" shaped exhaust ports but the 6.0 heads have "D" shaped ports.

[SRT10KLLR]

I am going to put on a turbo but it is a STS rear mount. I noticed a little carbon build-up on all the exhaust ports from the 5.3 manifold that were removed for the engine install. So if the stock 5.3 heads had a restriction at the manifold the P&P 6.0 heads will probably have a bigger restriction since the ports are different in shape and look larger.

Would I gain anything by switching to the 6.0 manifolds?

[SRT10KLLR]

Can I get away with the stock 5.3 manifolds for a while until I get the 6.0 ones?

[SRT10KLLR]

Thanks, Quick