Howdy Again:
Yes, Malcolm, You will need to flare out the top of the adapter. Think of it as countersinking a hole for a screw. The intake manifold is cast onto the head, but there is a soft metal carb adapter that goes between the carb and the cast manifold. That is the piece that needs to be flared. The stock carb hole is 1 1/2". The throttle bore of the 1101 is 1 11/16". So, I took a rat tail file to the inner lip after stuffing an oily rag down the hole to keep filings from going into the engine. You will need to file around the top until the butterfly valve of the 1101 clears the lip. This is not ideal, but you will notice a nice increase for an almost bolt-on upgrade.
Ideally, you would want to bore out the carb hole to 1 3/4" but that would require that the head be removed and you can fine a machine shop with a drill that big.
I vote for a DS II also, but if you can find a core in the recycle yard you can get the distributor, coil, module, wiring harness and plug wires all for the same price. Then clean and assess before installing.
Adios, David