An interesting little tidbit: apparently the browntop ZC and the EW/D15A3 blocks mate with little to no problems, aside the fact that no-one has figured out what timing belt to use yet There was some discussion about it over at redpepperracing.com, but it hasn't been updated for a while. I've been seriously considering buying a ZC head and a D15A3 block and seeing for myself.

Granted, these are both pre-88 engines.