master cylinder upgrade and offset ?

It looks like going from a 4-bolt to a 2 bolt MC is the starting point. Most of the 2 bolt MC's that I have looked at appear much smaller in overall size compared to the 4-bolt that I already have. I don't really want to go as far as converting over to the hemi adjuster block and have to drill another hole in the firewall. I don't need much room to clear the valve covers as it is. A 1/4" should do the trick. I don't want to spend the 4-500$ on the SSBC MC to get the clearance, when I have other things to buy to finish the car hopefully this spring. I can always add it next year once it is on the road.
Thanks Mguner for the reply and help.