350 help

[rennalds]

First off I know there are going to be a ton of opinions on this and a ton of ways to go. My son has a 71 c10 with a/c and a 350. The 350 runs pretty good, but we are looking for another 350 to buy and build it slowly throughout the rest of the year. Been lookin on craigslist and there are a ton of 350's but how do we know if they will fit(be the easiest to build/mount for his application). Thinking bout starting with a short block and building it up from there but definitely want to give him an increase in power. Also heard the blocks that take the short H2O pump are the best??? Any comments or ideas would be great not looking for a complete how to just something to get us pointed in the right direction.

Thanks