New timing chain, allowable slack?

The other set I tried is a billet ProGear/Avon one, and it was barely any better. That said, I put the exact same kind (ProGear, not Edelbrock) on my 360 the other day and it was a pretty tight fit, but I don't have any way to measure the distance between the crank and cam to compare the 2 motors with any precision. I figured the tensioner was an option, and even though it seems to have more supportes than haters, I don't want it to be considered a "bandaid" in this case. I know Cloyes makes .005" & .010" undersize timing sets, I figure I'd have to order one up and check fitment, then return it if it doesn't... but I haven't called them yet to see if they can recommend one from my rudimentary measurement.