Pointers? Yes, leave smog gear alone. When you fix the real problem, it should go 90 mph and up a hill lickety split, even with the smog gear.

The most common problems with an old Datsun are fouled plugs and cracked vacuum hoses. The plugs you can easily inspect, if they are tan color they are most likely good and have been firing OK. But there could be any problem, like carburetor setting is off or something. If you wish I could inspect it for you, perhaps around 7pm either FRI or SAT night. Or even Sunday night.