So you wont be needing the head gasket and rocker gasket I sent you unless they will be of use if you get the 2.3 engine from the Merkur XR4I? If I was you I would go for the engine which will be the easiest straight swap as the others will need quite a lot of modification and could end up a lot of hassle. The older Fords had lots of parts from different models which can be interchanged.Keep it as simple as you can and you should be ok.