I was reading these posts again and got to thinking 300 HP would be nice of course. But if I can get the 52 Merc Flathead I have up to 150 HP I would probably double the horsepower in my 51. I would be suprised if that tired 229 Flathead 6 is putting out 75 HP.
I've got an extra block that I will deffinatly be stuffing a 4" crank into, and build the rest of the motor for low RPM (below 3500) work. I've thought about a small blower but am worried about cooling issues while pulling a load. If you think bout it a blower is kinda a budget part. You will spend just as much on a blower as you will work and parts on a naturally aspirated motor and come out with more HP. The little 239 I've got now pulls good so I figure a little extra CID can't hurt. I would guess in a Hot Rod a person could get around 300 reliable HP.