Use a second compatable, cheaper cart to attempt the translation. Put the PCB in the Terranigma shell and save the original to prove that you own it.
Anything above 16Mb is very difficult because the pinouts are so different from any standare EPROMs. Check the SNES Kart document for N ROM pinouts and check against the cart you use. I haven't attempted a 32Mb translation yet, maybe later this year.
16Mb is easiest accomplished using a cart with 2 8Mb ROMs. Anything 8Mb or less is relatively easy.