If you're set on a 454 small block, why not build a Dart block Ford small block. They're designed to take a 4.125" bore, and any one of the crank manufacturers can supply a 4.25" crank = 454 cubes.
With the right cam/cyl heads/compression/carb combo and those cubes, I'd be disappointed if you didn't make 500+rwhp......
.....and it's keeping the right brand of engine in the SPF
