R30BC- In my opinion i would jus change your car.
Ive been in your place, had a 1.2 dynamique spent about 3k on it in modifications but the only thing that was lacking was the power.
I went back to my local renault garage to enquire about up grading then found out my monthly payments would go up by another £60 a month and insurance was another £120 for the year, plus out of it i got a good sound car with traction control,climate control and a nice bit of leather interior.
Trust me the upgrade is well worth it.
I know that i was told to put my car back to standard as good as possible which i done and that was it.
I did ask if it was worth doing an engine transplant and after all decided it was,nt worth the hassle- pm me if you got any more you,d like to know
James