" Taking a look at the intake
" Taking a look at the intake as I described above is a good way of distinguishing between a big block and a small block.
On a big block engine the intake (the part that the carberator is mounted on) will be almost as wide (from one head to the other) as it is long (from the front of the motor to the back)
On a small block the intake will only be about half as wide (from one head to the other) as it is long (from front to back).
The reason it makes a difference, is because as I said 300hp out of a small block can be done but requires a lot of work, a lot of aftermarket parts, and quite frankly only someone who is into extream speed such as a racer would care do do such a thing.
If the guy who built it is a racer and he built this motor for racing, and it dyno'd at 300hp then it is probably a really hot 351 windsor which is a small block. A big block built by a racer for racing would likely turn more than 300hp.
The concern I would have with it, and if he is a very good mechanic and he really did build it for himself he probably has it covered, is that when you beef up the top-end of a motor to produce way more power than the motor was originally designed for then you are going to stress the bottom end.
If this motor does not have four bolt mains then that added power is going to really test them every time you throttle up. If he did not go with an after market crank then its the same story.
Also if he stroked it, or bored it, then that changes the overall cubic inche displacement (usually to accomodate increased fuel consumption). There would likely be an aftermarket cam with increased lift and duration over that of the stock setup, along with aftermarket intake, carb(s), modifications to the heads, and any number of home grown changes all in the name of squeezing out a little more power.
All of these things are fine if your interest is going fast for that next race, but each and every one puts you at a slightly elevated risk of failure over the long haul. They will also offer poor fuel GPH because economy was the last thing that was important. The whole idea is dump and burn as much fuel as possible. The typical racer is going to rebuild/replace his motors frequently simply because they are a short life design. If you do not know this fella, really well, I would have to wonder if this is not just last years racing motor.
If it is a big block, then cranking 300hp would only suggest a well built motor perhaps with a little minor tinkering and should probably be ok for quite a long time as long as it is not abused. But, that would be SO "not like" a racer.
Just my two cents. Hope it all works out for you. "
