shave an 8n head a lil.. then check valve clearance with putty and no head gasket.. then relieve as needed and bolt on.. that's about it.. as dean and the others said. other goodies not so available.
and the merc pistons in the parent bore.. well.. it works.. bat can cause issues later and requires overbore to correct.
also don't give you much more hP.
if you have an 8n and want more hp.. get a naa or 6xx ( or 8xx and have near 2x hp )