Don't know much about the 326, but the 318 poly is the same short block as the more modern LA 318. It just has different heads, solid lifters, and clip type wrist pins as opposed to press fit, but most bottom end parts will interchange . I built a 318 poly years ago and actually used the crank, rods and pistons from an LA 318 in the 318 poly block. you might wanna check the specs and compare, it may be possible to use 318 LA parts in your 326.