I always thought CRR was the LS-6 block. In any case, there is a complete engine on ebay, bids are still under a grand. Wish I had the cash to bid, but just bought my 4290 heads lastnight!

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=2464351744&category=33615&sspagename=STRK%3AMEBWA%3AIT&rd=1

CRT is a LS5 w/manual trans. The LS6 had CRR for TH400 and CRV for manual. Note he says, "INFO ON MOTOR THAT I RECEIVED IS THAT IT HAS BEEN BUILT TO MATCH SPEC FOR LS6 MOTOR" and not that it IS a LS6. I suppose if you used LS6 internal parts, the above could be considered true.