Big block, early a transmission mount

Your question is a bit confusing. What exactly do you have parts-wise? Are you using an early A crossmember? What transmission? If you've got the early A-body crossmember, it should work with with zero problems. Is your 440 mounted? Maybe it's not where it's supposed to be front to back. With the engine and transmission bolted together, hang them in place and use the transmission crossmember to locate everything fore/aft.