xr2i 16v donor car, swap the lot in.

1.25 isn't worth gettin the spanners out for. sorry mate.

1.4 could be done, and would be a bit more worthwhile, but again you'd need a donor car which would probably be worth more than the car you're doing up? also i suppose not a lot of people bother because of how easy it is to buy the shell youve got with more poke in the first place, so there wont be a lot of info out.

a 1.4 cvh from an si mk3 in good nick woud be more worthwhile and cheaper, but youd be better off swapping your rep bits onto that car as it's already built up, and less work, and insurance.....

the cost of insurance would be more or less the same anyway for either swap due to the "engine change, same make different model" way they list it. as long as you're not adding forced induction, nos etc then it all comes under 1 bracket.