95-98 cluster (speedo) to work without electronics (ECU) etc

[GMT454]

Hi guys, I have a 98 silverado and took off original 6 cyl engine, and all its electronics to replace with a 454 ci carbureted V8, can I still make the speedo work with out the electronics? please advise. I have connected the tach directly to the distributor and works great.

 

[eyesi]

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[GMT454]

I have the ability to convert the pulses to voltages now, but what is the voltage trange for this generation cluster?