when i make a repro i buy the original version.
a example, i have chrono trigger original NTSC and original SFC, i have manufacture a German translation Chrono Trigger Repro and i use the case from the SFC cardridge, rocks perfect

only problem is from the fanmade games like Starfox 2 (Starwing 2), Zelda BS etc...
for this we have this great site :-)