What do the pistons look like, I think the cheapest way would be to try to use some other production pistons, or even get them made, maybe in 1275 and use a SA 1100 crank.
For the injection pump, it should be prety simple to get somekind of keyed adaptor made up, also I thought of was the cam that was extended for the pump.
I looked into using 1100 block, crank etc: many years ago and having pistons made ( now, of course, it would be would be 1300 ), but I think the lowest price that I cold get them down to was the same as twenty sets;
Also, the "nose" on the crank is an inch longer, with another key, for the drive to the injectors.
We are not talking about a lot of horsepower, even turbocharged, so if a bolt on tail will take SCA or twin cam Cortina power, a good welder ought to be able ti stick a tail on.
I wonder if Gorilla glue would do it?