Blowing fuses... is probably a bare wire. Just trace it out and see. Otherwise a bad shifter. That shouldn't be too expensive either.
As far as the engine... I've run a 427 a little bit. It'll run with a DT466 provided you jamb your right foot to the floor and keep it there. The 366 will probably be a bit shy of that... but keep it wound up and it should make decent power.