I've just put a standard L20b plus twin 40s 5speed and good pipes into my 120y. I'm happy with the whole thing . It's a lot of fun to drive. However the conversion is fairly involved. Cross member is way easy, gearbox mount, clutch pedal box and way heavier front springs(the L series is not much heavier than the A but the gear box adds to the weight) also bigger radiator. Cut an extra hole for the gear shift. And cut down the tail shaft. The whole package is a lot of work! Plus engineering, and not to mention insurance!