Seen people epoxy the plugs and tap and insert pipe plugs, but in the end the $30-40 for 2 quick welds is worth it. Make sure to get one of Tom's plates for the bottom of the intake to preheat the intake.
'45 Ford PU 66 Valiant wagon, leaning tower of power. 79 Chevy C10 w/250 02 PT Cruiser Convertable