I liked my old 8v lump, was a good unit not that slow either.. was as quick as the 16v car i got for the gearbox..
id prob not bother converting from 8v to 16v (unless your 8v lumo has died?) other wise id go 20vt (can be expensive to do) or VR6 it (can be done cheap) we did Benvictors and the car moves well, its much better than a valver thats for sure