ma71 supras did come out with manual and targa roofs. but none of them came out with 1jz's (that i know of). im pretty sure jza70's came out with targa tops but i havent seen to many. most people prefer the sunroof as it offers more structural reliability. i would not bother with an auto to manual conversion. my sugestion is that if you do not find a 1jz manual with a targa roof is to get a 7m powered supra and fit a 1j but i dont think the engine mounts are the same.