Claim of 25% HP bump true?

[1928 Sport Coupe]

Originally Posted by brito36

With all the conversations on increased compression, larger carburetors, and intake manifolds, I would make sure that my lower end could handle all these improvements.

I would like to install a High Compression head in either 5.5:1 or 6:1 such as Snyders, a "B" cam, a "B" carb, and a bored out "A" intake. If I were to use new poured Babbitt mains and rods would that be sufficient for the improvements I want to do? Which head would be the better choice, the 5.5:1 or 6:1? I have been told any HC head could destroy the center main bearing if you drive it at all aggressively. I would just like to be able to keep up with traffic when needed.
As far as I know this is the original 35K miles engine in the car (1930 Town Sedan) and I would like to keep it in the car. This way I could always return it to stock.

Thanks