Unless you are dead set on spending a ton of money and having an aluminum block, I have an alternative.  Get an Lq4 out of a newer chevy truck.  You can then put LSx heads and intake on and have a cheaper, high power engine.  You could even run the Lq4 setup until funds became available to upgrade. Just a thought.  I've seen decent mileage Lq4's go for less than $2000 complete. 

yah i read somewhere the l92 head was the same casting as the ls7. i have found prices to vary ALOT on these parts.