318 For Fun

I'm thinking that when I started inquiring about the 318 that I might have not been going about it the correct way. I'm wanting to improve the throttle response and low to midrange torque. Most likely the 318 will never see over 5,000 rpm's, I don't want or need it to be able to spin 6,000 plus rpm's. From what I've read on here is that the smaller port heads are best for port velocity and velocity is good for torque, correct? So wouldn't speedmaster's 171cc heads be to big for what I'm wanting to do? Is there a aftermarket cylinder head ( cast iron or aluminum ) that has smaller ports? I'm thinking about running the pistons at zero deck height and wouldn't I be better off with a closed chamber heads? I know that I've been giving a lot of good advice on here but as I've reviewed some of the material it's mostly focused on more power than I even need or want. I'm not looking for a 12 second car by any means. Also wouldn't the magnum heads have to much port velocity? Now as far as the cylinder heads cracking, does this effect the performance of the build, can the cracks get worse and cause more damage later on? I've talked to a machine shop and they recommend hot tanking the block and then checking the main bearing bore alignment and once this is done with then he would check block deck height and correct it if needed by decking / squaring the block and then bore and hone the cylinders with torque plates, assembly will be balanced too. Compression ratio in around mid 9's.