Why not just get a b16a block and sleeve it out to 84.5mm. It would be a 1.8L with a 1.74:1 r/s ratio. You could rev the shit out of it and it would cost alot less. B17a cranks are nearly impossible to find but you can pick someones b16a shortblock up for $150, hell I gave away one of my b16a shortblocks in running order for free before. There is no reason to use a b20 block, it's cylinder walls would be weaker too when compared to a sleeved b16a block.