If the guys who design these engines actually used them they would know a rear carb, rear exhaust is what we want and the one configuration that will fit the majority of models.
Only the really short cowl types, fokkers, sopwiths etc that might have a problem, but even then the carb can be made to go through the firewall.
I personally would'nt buy another side carb petrol, no model I can think of I want to build, that a rear carb would'nt be the best option.
Same with exhaust how many aircraft want them to come out the side, rear bottom is 95% the best option.