1970 factory service manual, front suspension, page 2-14 says "crossmember bolts...150 ft lbs".
That means clean threads of course and light amount of oil (one or two drops) on threads. Some of this kind of thing I don't use oil, instead apply two lines of blue locktite, that way no water can get to threads, the fastener will stay tight, and disassembly will be no problem in the future.
