413 marine industrial (E) engine, to, not so industrail......

I believe the 516 heads are closed chamber small valve. All bb heads 66 and older have the small valves. I bet I have a pair out in the shop laying around but shipping iron heads = not good $ense. Seems I can't give them away these days. I scrapped a dozen pair last year to get them from under foot.
Still have a dozen pair of 906 and 915s. Couldn't bring myself to scrap them all. With the cheap stroker kits and aluminum heads available today nobody wants to invest in them.
I like the iron heads myself (in with the minority here) they seem less lazy and more crisp.
I do have aluminum heads on half my engines but only because of the weight loss.

Sounds like a fun project keep us posted how this comes together.