Bob - What you are experiencing is what's been going on in the 385 world for a while now. Yes, there is alum. blocks out there but they are not so easly had.
Understand that the Aluminum blocks out there weigh just as much as the equilivant stock and some aftermarket blocks and are not any stronger than the aftermarket stuff out there.
And you will start to understand why there is not much interest in aluminum blocks by in large.
For a rundown of the stuff out there I suggest the following sites:
www.network54.com/forum/85220
www.eliminatorproducts.com
pay attention to the high carbon block- Formula I stuff......... They also manufacture tall deck blocks too.
cobrashock