Thanks for the info, to be honest I wasn't even thinking of the little holes for bolts and drain tubes. I'm thinking of making something to mount the original blower motor to seal that hole and using the original heater hose grommet and looping the heater hose thru the firewall so the water circulates and making a plate for the AC control valve hole. It will look like it still has a heater at least and the rest of the smaller heater box mounting holes I'll seal up with some round head machine screws, washers and nuts thru the fire wall.