I haven't seen a ZX Spectrum implementation on an ice40 chip.
There is an FPGA implementation in the Mister project. That is partly Verilog and partly VHDL. The Z80 implementation could be replaced by a Verilog implementation like that in Ice40CPMZ80 or iceZ0mb1e.
The SDRAM would need to be replaced with SRAM, so perhaps the port would be easier on a Blackice Mx.