[RodKnock]

According to their websites, the blocks weigh as follows:

Pond block = 120 lbs
Shelby block = 125 lbs
Factory FE = 195 lbs
Genesis block = 230 lbs

Also, the max bore sizes are:

Pond block = 4.310"
Shelby block = 4.440"
Genesis block = 4.440"