Stock block plus 2.000 sbc rods, longset stroke?

Bouchillon Performance Engineering (BPE) offered both the 4.125 and the 4.250 crank a few years back, I don't think you'll find the 4.250 available anymore, besides I think it used the Honda con rod not the 2.000 chev size you suggested.
DJVCUDA worked on something in the 430 cid range if you search his post about 8 years ago.