<VV> Head Fins: How Smooth/Clean?

[N. Joseph Potts]

I have a heat-challenged situation in my 66 Corsa 140hp that I like to run
with stock distributor and ignition timing, and with stock shrouds. The car
is air conditioned, and that, too, is stock (A/C condenser is upstream in
the path of the air that cools the engine). I live in a hot climate, but at
least I don't drive up long hills/mountains, and I don't pull a trailer. If
I use regular gas, I get ferocious ping. Premium gets me by with about zero
headroom on hot days.
     I'm preparing a pair of (stock) heads for use in this situation, and I
have just "deflashed" them. Naturally, there remains a vestige of flashing
at the narrow point of every through-passage, and I'm working on smoothing
these down (not easy, as anyone who's tried it knows). I'm working on the
understanding (not confirmed) that the closer I can get these flash vestiges
to disappearing, the better my heads will be cooled. And this exercise
brings me to thoughts about the REST of the cooling fins that the cooling
air passes over (the parts upstream and downstream of the point where the
flashing is found).
     Obviously, the cleaner these fins are, the better for cooling.
Obviously, these fins get dirty in use (I'm tempted to spray coil-cleaning
chemical into the ductwork of my assembled engine). But I'm still getting
them as clean as possible so that at least they start off as effective as
possible.
     My real question is, should I bother to polish them (make them smooth)?
Could/should the FINISH of the fins have any effect on their cooling
capacity, particularly after said fins have acquired a patina of dust and/or
(shudder) oil or grease? For the reasons described above, I need all the
efficiency I can get.
     If anyone has any actual experience to report from, or solid
thermodynamic theory, I'd love to hear about it, preferably in a POST to the
list. Thanks.

Joe Potts
Miami, Florida USA
1966 Corsa coupe 140hp 4-speed with A/C