probably not impossible to have a manifold fabbed up by a good machinist.
webers worked real good on older europen 4cylinders,to be honest they are superior to holleys and edelbrocks by design since they realy dont care to much about the pulses wich the holleys and edelbrocks have so much trouble with handling.. the trick to make them work exept for tuning is to get the runnerlenghts and stacks right.