Cool, & Thx for the pics.

Those ports appear to be pretty good size.

I would not think to open up the ports to gasket match them.
They look too big already, might be low on port velocity?
Hard to say, by just looking @ the pics.

Maybe if you had a measurements of the intake ports & exhaust ports I would have a better idea on just what size those ports are.
Valve sizes in, ex? I forgot.

I would definitely not lower the floors of the ports. You would want to leave those floors alone, unless there is a big mismatch between the intake manifold & the head.

On the 1 BBL intake , are the ports divided?
It's been so long since I have the seen the 1 BBL & 4 BBL Pontiac Sprint 6 intakes side by side I cannot remember how they looked.
Got some pics?

Did the 4BBL Sprint 6 have better con rods than the base line 1BBl Pontiac 6? I heard they did but never confirmed it.

Your paint job on the engine makes it look new.

MBHD
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12 port SDS EFI