Also remember for the longest time for a while in 1973 to 1987 the speed limit was 55 , some places 60 on interstates.
https://en.wikipedia.org/wiki/National_Maximum_Speed_Law#1973.E2.80.9455.C2.A0mph_National_Speed_Limit
just drive it, its not going to hurt anything, christ you could almost run straight water as low as the compression is on these smog era small blocks, wont hurt a thing.
***** a waste of money anyway.