516 heads closed camber cc volume?

Your english is just fine. I've used the 516s a bunch. Good low budget head. The ones I've measured were always at least 84cc with a few individuals as large as 86ccs. I've read they were smaller but IMO this is the result of earlier valve jobs where the heads were milled. These used to be standard maintenance on the 60s engines so someone that didn't know what to look for might think the engine was factory. Depending what your long-term plans are you could probably get away a bit cheaper by not doing the exh seats. These heads had problems with core shift - so adding the 1.74 valve and the required larger hardened exhaust seats might be fatal. If you want the larger exhaust valve have them put on the existing iron - don't replace the seats with hardened. And figure the heads will be junk the next time they need valve work. The aluminum heads will cost a bit more new, and both new or used should be checked out by a qualified shop before you just bolt them on.