ae111kiwi

I have a 16v bluetop that I am having rebuilt by a mate, only to find out the head has gone missing at a mates house. He said it must have been lost while he was moving it between garages. But he does have a blacktop 20v head sitting around with the ITB's and a loom/ecu I can buy for cheap. Is it worth putting the blacktop head on the 3 rib bluetop block or would it make it slower? Should I just try and find another bluetop head? It is to go into an ae85.