You could use the front fitting second series motor mounts from a 55-59 truck, there's a picture of these mounts fitted on my '50 Chevy truck here.
http://i103.piczo.com/view/3/h/b/5/2/u/p/w/0/w/z/t/img/i283585210_46531_5.jpg you just need to put a simple crossmember immediately behind the original one at the front of the chassis. This gives you more space round the motor and more freedom with your exhaust manifolds/header setup than the mid mount setup.
Stuart.
