I'm planning to convert my 350 from carb to EFI. I'm wondering where the knock sensor would be installed on an SBC?

Usually threaded into the side of the block in place of one of the drain plugs.

For an OE TBI system, pass side coolant drain in front of the starter.
For OE TPI system, underneath the plenum on the manifold, one for each bank.

Thanks guys.

I'm actually converting an LT1 intake to add a distributor and coolant lines, but will be using a TPI 730 ECM that I already have to run it. I'll have to see how this works out because I know the LT1s had the knock sendors in the side of the block, at least that's what I remember.