[Bart Carter]

From Ford Racing:

Cast Iron:
302 street replacement production block, max 347 cu in, 135 lbs
302 race block, max 360 cu in, 160 lbs
351 (9.5" deck) production block, max 427 cu in, 190 lbs
351 (9.5" deck) race block, max 454 cu in, 205 lbs

Aluminum:
302 race block, max 380 cu in, 92 lbs
351 (9.5" deck) race block, max 454 cu in, 122 lbs

Aluminum blocks have steel 4-bolt main caps and replaceable cylinder bore sleeves

A 454 aluminum small block with the weight of a 5.0 sounds mighty tempting.