Re: opinions on 350 GM Goodwrench motor with E tek heads?
12530283 is the 4-bolt version of the L31 long block. Seems more or less the same as the 330Hp crate motor minus the chrome, but has a different camshaft.
Alternatively I think 12556121 is the L31 short block (1 piece main, roller capable) but it seems to be discontinued.
As far as the idea of buying a base long (or short) block and bolting on your own heads, cam, etc -- definitely a good idea provided you can match the parts reasonably well...
If you're going to dump the heads anyway, you should be able to find a GM Goodwrench short block for somewhere around $1000-$1100 range (I had part numbers someplace, but can't find them right now....)