If those bolts have been in there since the '70's, they probably have enough carbon/rust in the threads to seal them. I would just run it with whatever is in the ports and decide if it's worth messing with, if it ain't broke, don't fix it.
1957 Chevrolet 5700 LCF 283 SM420 2 speed rear, 1955 IH 300U T/A, 1978 Corvette 350 auto, 1978 Yamaha DT175, 1999 Harley Davidson Softail Fat Boy
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