Short of finding one of the 'Rare' Siamese blocks designated for Nascar in the mid/late 70's that were cast in the USA then shipped to Aussie for machineing etc its a 'Risky Business' Im even more conservative than these guys when it comes to the production blocks, wont bore them past 4.030", wont build them with less than a 6" rod even at 3.5" stroke. Why, I learnt the hard way---- the more you stroke em the more they broke em'
& I hate doing things twice for no good reason.