A friend of mine use to have a GVP 1260. Great card, except for the 64-pin SIMM prices. He had a 16Mb SIMM on it.
BTW: GVP made SIMMs in 1, 4 and 16Mb "flavours", all 60ns. That's why the performance was so great.
There is a hack on aminet to "make" a GVP SIMM by ordinary 72-pin units. Ugly as hell, but works!