57 Chevrolet Corvette Gasser problem

I have 2-3 of the Chevrolet Corvette Gasser kits. Just started one and came across a problem with exhaust/header pipes. Having a hard time with them fitting and lining up with holes in the engine block I've glued the exhaust pipes together at the ends where the header pipe attaches but now the ends that attach to the engine either does not reach or line up with holes in the engine block. Anyone else have this problem. Won't be a problem really as that part won't be that visible when the engine is installed. I plan to add the sidepipes and install this engine into a Camaro.