The bores require the addition of sleeves, so bore size is up to you. As you can see from the photo's provided on the 1st page of this post there are bosses to accomidate the use of either a 10 bolt factory style head or an aftermarket 18 bolt head. Main size is custom as to what you want (2.5", 2.810", 2.25"). You can put a stock stroke 340 crank in it or a 4.250". It's all up to you. Hope this helps.
Rod
