I only checked out the second link as well and there is certainly some good tips on flathead tuning there. On the flathead 4 cylinder Ford engines I used to tune up the trick was to take the top ring off the pistons and relieve the block down to just above the second ring taking care to stay inside the head gasket sealing area. They would certainly breath well then
With tuning a flathead raising the compression doesn't count for much, - it's getting them to breath well that will raise their horsepower.
Something I didn't understand though was how everyone in that thread was talking about using a grinding tool like the Dremel. Yes I did use a grinding tool to open out ports and smooth them off, but block relieving I always did with ordinary files. This is one place where taking your time and working to get a good shape and smooth flow really pays. Not to mention that it's far too easy to accidentally ruin valve seats or the cylinder bore if you slip with a grinder.
