[Coley]

That engine is better suited for a lighter vehicle,....particularly a car. The specs say that it is not recommended for anything over a 6000lb GVW...and would definitely include not being suitable for a 3/4 ton.
Your C20 (3/4 ton) definitely exceeds that 6000lb GVW capability. That said, I think you might be surprised to learn that your 3/4 ton is probably over 4500lbs in its weight. I very highly recommend you run it over a scale somewhere to check and confirm this....you might be surprised.
Many people misunderstand the 'base listed weight' as the weight of their truck. The base weight is usually the base engine (6 cylinder?), standard trans, no power steering, etc, etc.
As an example my 72' 1/2 ton is just slightly over 4000 lbs and it doesn't have anything near as heavy as your running gear, 3/4ton frame, bigger tires, springs, etc. It does has ps/pb/350/a-c...and all this adds weight.
You might be better off, as many have recommended, to get the 260hp and do some bolt on upgrades to get an engine better suited for your truck weight.
My two bits.
Coley