Well not saying it can not be done and done good with a big block. But man that is a lot more weight and twist in a convert. I would reccomend a stroker small block.
Less money and will handle better for less $$$. Go with a 360 stroker 408. Best bang for the buck!
And I would do a complete restore of the entire suspension and at the same time add a nice set of disc brakes up front and maybe some .890 torsion bars too!
Great looking ride!