kpl70sx

We had an aluminum radiator custom made from a place called Alumi-tech in Michigan. It's going in a 64 Cutlass that currently has the stock core support in it. The problem is that the new radiator will not fit in the stock brackets - lower or upper. We also need to fit the stock fan shroud back on the radiator. The new radiator is 2 3/4" wide. It seems that it may fit into stock brackets if they were for a 4-core. Was there a 4-core option in 64? If so, would this work? If not, what would? Or will we have to fab up new brackets?
Thanks for the help.