Then someone put a Rochester on your motor. The last Rochester carbs were new in 1989
BTW, the mercarb is a Rochester clone with a single idle adjustment screw. The mercarb has a single screw
Check for spark. If you have the original 2-wire distributor sensor, I suggest you spend the $50 on a new 3-wire sensor
Also check the oil pressure switch (not sender). The oil pressure switch controls the fuel pump
Pull drive
Disconnect battery cables
Disconnect harness
Disconnect exhaust
Disconnect fuel line
Disconnect cables
Remove lag bolts from front mount, pull rear mount bolts
Lift motor out
If you have been removing the drive every year and keeping on top of maintenance, that whole process is...
In neutral the motor will spin to 5000rpm on 2 cylinders with a gummed up carb.
Doesn't mean anything, and you run risk of destroying the motor
Motor in pic is a vortec
Is there power in the red wire at the key switch ... Yes or no
If no, work your way back to the battery and find where you have power
If yes, work your way along the purple wire until you don't have power