Blue,
If your sole concern is resale than the 427 or 428 bb is your choice. However, no many of us build/buy these cars for their resale. We have them to DRIVE. But if that is your concern then fine.
As Klayfish so eloquently stated, many of the Joisey boys have smallblocks. There are some exceptions and I hear there is a REAL one around with a side oiler....what's his name again?
Small blocks are less expensive to build, parts are more readily available, more room to work on them and, I believe, better track performance. Plus, a stroked small block can put out well over 500 hp.
Take a look at The Engine Factory web site.
http://www.fordcobraengines.com/
Roscoe