ohn, for a quick reference, the 351 windsor has the distributor running through the front of the intake manifold.
Not quite
I have a 1969 351w I just finished rebuilding, the distriutor does not go through the intake
In other words, I do not have to pull the distributor when or if I pull the intake.
(edelbrok #2181 intake, 9.2 deck height block)
The distributer is nested directly on the block in front of the intake.

as for the 351c or w side by side, easy for me.
The valve covers gasket flange is rectangular on the 'c' and rounded off on the 'w'.