a had a 2door 1000 for a couple of years that i built with a fairly worked A14, had a A12GX head port/polish and L16 exhauast valves, double valve springs balnced bottom end, extractors, 2 1/4 exhaust, twin 40mm dellortos, 1600 disc brake front end and 120y diff assembly(couple inches wider than 1000) sprung button clutch and 5spd. of the 4 dattos and couple other cars i've owned she was the sweetest. revved to mid 8000s and didn't miss a beat
personal opinion - stick with an A series, easy swap, easy to make go fast and damn cheap to fix
no offence to the fuel injected newer engine conversions but the sound of twin 40's wide open . . . . a joy to the ear

gee i miss her