Your swap has been done before, I have seen a few.
I think one good place you have to check out is the LS1Tech forum (
http://ls1tech.com/forums/. It specializes on 3rd Gen chev engines and there is a mountain of knowledge among the members of this forum.
Most people there are indeed into drag racing their street-driven their 3rd Gen, but in the Performance chapter, there is a section called Conversions and Hybrids (Hybrids being cars that never had a 3rd Gen engine from the factory, not the semi-electric cars!!!). There, anything goes. Chances are good someone there has done your swap; anyway, ask questions, people know a lot. During your swap, you probably will have questions about fuel system, harness... They know all that!
There is also knowledge that does not apply to you but that you can use, for instance where would the various aftermarket engine mount adapters put the back of the 3rd Gen engine compared to the small block; then you do your measurements
I have put a 6.0L in a '70 Impala, no one had done this swap on the site, but I could not have done it without the site!
Good luck
