[Bobcat]

My chassis is # 757 ... I think my wiring harness is like yours ... maybe B.P. can chime in . I used the MSD tach output , but had to run a wire ( orange was my choice ) from the MSD tach output to the orange wire labeled #40 in the ERA harness . I ran/connected the red from the MSD unit to the white wire labeled # 40 in the ERA harness . You will have to furnish the wire from the tach output as it isn`t supplied .
The MSD white wire is only used if you want/have a kill switch .... tape it up . Orange from the MSD connects to the + of the coil and black from the MSD connects to - on the coil . These are the only two wires ( on mine ) that connect to the coil . One note ... ERA is very emphatic in isolating the distributor wires from the MSD unit to the distributor from all others . I ran them down the manifold valley on the driver`s side and ran the others down the passenger`s side . You can induce some really strange transients if not careful .
I`ve got the SW tach also , but ended up having to use the MSD tach adapter also .
x2 on what Charles said about expansion tank levels and richening up the carb .
Hope this helps .
Bob